Rate Of Desulfurization Research Articles

ENERGY EFFICIENT SOLUTIONS FOR STEEL REFINING IN FOUNDRY CLASS ELECTRIC ARC FURNACE

Analysis of recent research and publications. The technological period in foundry class electric arc furnaces (EAF) is usually long term, is determined by desulfurization of steel and accompanied by significant energy loss through emissive surface of shallow steelmaking bath. Known mathematical models of Sulphur removal do not take into attention the impact of hydrodynamics factors due to deepening of the steelmaking bath of the same volume. Purpose. The task is to show feasibility of energy savings in foundry class EAF due to implementation of “deep” bath with forced pneumatic mixing. Method. Numerical modeling of sulfur removal in the steelmaking bath under conditions of forced pneumatic mixing. Research findings. Mathematical model takes into account removal of sulfur on interfacial surface of thin steel film, covering gas bubbles, geometry of bath and two-phase region, hydrodynamics, coalescence of bubbles. Simulation showed that in a “deep” bath, having shape factor (diameter to depth ratio) 2.5, rate of desulfurization, increases up to 5-6.7 times compared with a standard not forcibly stirred bath with shape factor 4.5, due to amplification of mass transfer in two-phase region and film desulfurization, reaching at least 23-28 % in overall process. Rise of porous plug radius contributes to increase sulfur removal velocity due to enlargement of threshold flowrates, corresponding to transition bubble - jet mode and bath "breakdown” mode. Effect of bath deepening in overall improvement of desulfurization kinetics is on average 23%. Practical significance. The obtained results allow to expect a shortening of the technological period due to increase of sulfur removal processes by an average of 1.5 times. Taking into account the share of the technological period in the total duration of melting on average 25-30%, the reduction of melting time will be 8-10%, and the saving of electricity, with an average specific consumption in small-capacity arc furnaces of 850 kWh/t, is expected to be 60-70 kWh per ton of crude steel.

Effect of Liquid Fraction on Reaction Rate of Molten Steel Desulfurization Using Solid-Liquid Coexisting Slag

Effect of Liquid Fraction on Reaction Rate of Molten Steel Desulfurization Using Solid-Liquid Coexisting Slag

The Synergistic Effect of Na2O on Hot Metal Desulfurization Kinetics in CaO-Na2O-SiO2-Al2O3-MgO Slag System

An experimental and modelling study on hot metal desulfurization is considered. The study identifies the thermodynamic and kinetic factors that define the rate of permanent contact reaction in steady flow conditions. The study proceeds from defining the expressions for overall mass transfer rate of desulfurization and uses experimental data to identify the mass transfer coefficients. The study draws an estimate of the model parameter distributions using a real–coded genetic algorithm and a Metropolis Hastings’ algorithm. The results of this study and the literature data indicate that the Na2O content (5–20 wt–%) of the slag has a great potential for improving the desulfurization efficiency via the increase of the rate of the permanent contact reaction. The desulfurization efficiency increased 5 unit–% per unit–% increase in slags Na2O content (below 10 wt–%). This can be implied to potentially decrease the desulfurization reagent consumption in powder injection.

Effects of Liquid Fraction on Reaction Rate of Molten Steel Desulfurization Using Solid-liquid Coexisting Slag

Effects of Liquid Fraction on Reaction Rate of Molten Steel Desulfurization Using Solid-liquid Coexisting Slag

SO3 removal rate and emission test of the limestone-gypsum wet desulfurization system for coal-fired power plants

This paper studies the SO3 removal ability of dual tower wet desulfurization (in series) and adopts a combination of on-site flue gas sampling and laboratory condensation control. A dual tower (series) supported boiler is used. The SO3 content in the original and clean flue gas of the dual cycle wet desulfurization device was measured, and the removal rate of SO3 of the device was measured. Desulfurization is calculated on the basis of the influence of unit electrical load, coal sulfur content, and desulfurization (raw material flue gas) inlet particle concentration on removal rate. This paper discusses and analyzes the SO3 and SO3 emission concentrations for SO3 removal rules in desulfurization systems. The results indicate that the total sulfur content of coal is relatively high, and the concentration of SO3 is relatively high. The traditional flue gas and net flue gas content in the dual tower wet desulfurization system (series) is relatively high. When burning sulfur-containing coal, there may be “blue smoke” in the flue gas. When the unit load changes between 182 MW and 350 MW, the SO3 removal rate of dual tower wet desulfurization (in series) is between 46.7% and 65.3%, with a net flue gas SO3 concentration of 16.0 mg/m3∼20.5 mg/m3. Due to equipment layout and other reasons, the SO3 removal rate of the primary tower is lower than that of the secondary tower. The removal rate of SO3 is also affected by the concentration of original smoke particles. Due to the condensation of SO3 on the particles and the dust removal of the adsorption tower, the higher the concentration of raw flue gas particles is, the higher the removal rate is. SO3 will be higher. The study also suggests the SO3 removal ability of double tower (series) and double ring wet desulfurization, which is better adapted to changes in load and coal. The next step is to explore the SO3 removal capacity of the dual tower system by optimizing its operating parameters. In addition, due to the arrangement of a desulfurization system after dust removal, it is impossible to control the SO3 source. Subsequent research can control the production of existing SO3 through coal distribution and combustion control.

Synthesis of Carbon Nitride Supported POM‐based IL for Deep Oxidative Desulfurization of Dibenzothiophene

AbstractThe organic cation methyl imidazolium 1‐(3‐sulfonic) propyl (MIMPs) and the polyoxometalate (H3PMo6W6O40) were combined to synthesis [MIMPs]3PMo6W6O40 successfully, which was loaded on graphitic carbon nitride (g‐C3N4). The composite materials [MIMPs]3PMo6W6O40/g‐C3N4 catalysts were characterized by means of FT‐IR, XRD, TEM, XPS and nitrogen adsorption–desorption analysis (BET). Verified by various characterizations, synthesis and immobilization process could occur electron migration to improve the electronic and textural properties of [MIMPs]3PMo6W6O40/g‐C3N4 catalyst. At the optimal conditions of mcatalyst/VOil=0.1 g/10 mL, m[MIMPs]3PMo6W6O40: m[MIMPs]3PMo6W6O40/g‐C3N4=30 %, O/S=5 (molar ratio), the desulfurization rate reaches 100 % within 40 min. In addition, the concentration of aromatics had little effect on the reaction. Furthermore, the catalyst also shows high rate of desulfurization on real oil. The ODS reaction mechanism of this catalyst is also investigated.

SO3 Migration and Emission Characteristics of CFB Boilers

In order to study the migration and transformation of SO3 from circulating fluidized bed boiler (CFB) in the air preheater and flue gas treatment facilities, 10 circulating fluidized bed boilers with installed capacities between 150 MW and 330 MW were measured by controlled condensation method. Ten circulating fluidized bed boilers with installed capacities ranging from 150 MW to 330 MW were measured using the controlled condensation method. It is showed that the SO3 removal rate of the air preheater was affected by the air preheater flue gas exit temperature, which ranged from 6.7 % to 36.5 %, and the SO3 removal rate of the rotary air preheater was higher than that of the tubular air preheater. The SO3 removal rate of cloth bag filter and electric bag filter is above 40 %; the SO3 removal rate of electrostatic precipitator is between 6.1 % and 10.8 %. The SO3 removal rate of wet desulfurization method ranges from 41.7 % to 73.4 %, with the highest SO3 removal rate of double tower double cycle. The SO3 removal rate of off-furnace CFB semi-dry desulfurization reached 89.7 %~97.9 %, and the dry process inside the furnace + off-furnace CFB semi-dry process could reduce the SO3 at the desulfurization outlet to below 0.3 mg/m3 under the tested conditions. The conclusions of the test analysis in this paper can provide reference for SO3 control in circulating fluidized bed boilers and related policy formulation.

Numerical simulation of the dolomite in-situ desulfurization in molten iron

With the growing need for high-quality steel, the requirement for efficient deep desulfurization technologies is growing, and lots of research have be conducted. The desulfurization in hot iron with Mg produced in situ by the aluminothermic reduction of decomposed dolomite was simulated. The magnesium generated at the molten matte-slag interface is dissolved in the molten iron and desulfurizing while spread downwards The process has been studied by experiment and computational fluid dynamics simulation. Some analysis and assumptions were made for the simulation conditions and the simulated data are in good agreement with the experimental results. The rate of desulfurization depended mainly on the reaction rate and is almost independent of the rate of diffusion of Al, S and Mg according to the results. Under the present experimental conditions, the desulfurization rate increased with the increase in temperature and the amount of reactants. However, the effect is not obvious when the temperature is higher than 1623K. The adjustment in diffusion coefficient has minimal influence on the desulfurization efficiency. The desulfurization reaction is mainly in the homogeneous phase, and the proportion of magnesium bubble desulfurization could be ignored when the temperature is between 1523 K–1723 K.

Desulfurization of thar lignite by oxidative alkali leaching under pressure

ABSTRACT In this research work, thar coal was treated with NaOH solution in dissolved oxygen with different reaction parameters in an isothermal reactor. All three types of sulfur were removed from coal through oxidative alkali leaching under pressure. About 90% pyretic sulfur, 78% organic sulfur and 50% sulfate sulfur were removed, and more than 82% of total sulfur removal was achieved. Effects of various reaction parameters were observed, it was investigated that reaction time, agitation speed and partial pressure of oxygen have positive effects on the rate of desulfurization. Whereas desulfurization was increased with increase in reaction temperature and alkali concentration till optimum value as 120°C for temperature and 2.5 Molarity of NaOH solution for alkali concentration . While desulfurization was decreased with further increase in values of temperature and alkali concentration. The rate of desulfurization was observed maximum with minimum particle size of 40 µm. An Optimized reaction was performed reaction time 120°C oxygen partial pressure 200 psi, particle size 40 µm, NaOH concetration was 0.25 Molarity, reaction time was 3 hours agitation speed was 2000 rpm, after getting the optimum values of all reaction parameters. Processed and raw thar coal was characterized with Thermogravimetric Analysis (TGA) and Testo smoke number to investigate the combustion behavior of processed coal. It was observed that the combustion properties of processed coal were improved than that of raw coal and black smoke in processed coal was reduced.

Study on performance and function mechanisms of whisker modified flue gas desulfurization (FGD) gypsum

The high annual output and low utilization rate of flue gas desulfurization (FGD) gypsum cause acute damage to the environment in China. FGD gypsum board is a potential product, but its wide application is limited due to its poor mechanical properties and water resistance. Here, anhydrous calcium sulfate whisker (ACSW) and calcium carbonate whisker (CW) were chosen to improve the properties of FGD gypsum. The effects of two types of whiskers on the working performance, mechanical properties, and water resistance of FGD gypsum were analyzed and compared. The results show that the incorporation of whiskers reduced the processability of the FGD gypsum slurry. The mechanical properties of FGD gypsum improved greatly because the whiskers can increase the contact points between the crystals and fill the pores in FGD gypsum. The 7-day dry flexural strength of FGD gypsum with ACSW and CW increased by 46.99% and 33.07%, respectively. ACSW was better for enhancement than CW due to its good adhesion with gypsum. However, ACSW was not as effective as CW in improving the water resistance, because the structure of ACSW will be destroyed in a humid environment. This research focuses on improving the mechanical and further utilization of FGD gypsum, which also provides a theoretical basis for improving the performance of FGD gypsum.

A multi-objective optimization strategy of steam power system to achieve standard emission and optimal economic by NSGA-Ⅱ

In this work, the models of desulfurization and denitrification are added to solve the problem of SO2 and NOX standardized discharge. The design and optimization strategy of steam power system (SPS) considering contaminant emissions reduction technology is proposed to achieve the trade-off between economic and environmental goals. Detailed superstructure networks of desulfurization based on wet limestone flue gas desulfurization and denitrification based on selective catalytic reduction were established and embedded in the SPS model. Then, based on this combined superstructure model, a mathematical formulation of multiple objective mixed integer nonlinear programming describing the SPS coupled with desulfurization and denitrification was established. The steam flow rate, outlet enthalpy, the consumption of the turbine power of the direct drive equipment and the electricity generated by the turbine, the flow rate and efficiency of desulfurization and denitrification are chosen as the optimization variables. The operating conditions and equipment parameters of the global system are optimized. Finally, the second-generation non-dominated sorting genetic algorithm (NSGA-II) was applied to obtain the Pareto optimization curve, exploring trade-offs between economic and environmental goals. Two case studies are used to assess the applicability and performance of the optimization formulation and solution algorithm.

Numerical simulation of semi-dry desulfurization spouted bed using the discrete element method (DEM)

A research on semi-dry FGD technology using CFD-DEM method is conducted to study the motion of wet particles and their performance on SO2 remove. The liquid bridge force model proposed by Mikami (1998) et al. is introduced to estimate the interactionamong wet particles. The reaction rate of desulfurization is calculated depended on the two-film theory. The profiles of particle volume fractions, velocities and the main forces on particles are obtained. Simulation results indicate that liquid bridge force facilitates the formation of particle aggregation. Meanwhile, the distributions of particles are more inhomogeneous, which result in a decrease on SO2 removal efficiency. Furthermore, the effect of humidity on the desulfurization is also investigated by adjusting the parameter of dimensionless liquid bridge volume. As the humidity increases, the agglomerate grows and the SO2 removal efficiency increases first and gradually decreases. Simulation results of SO2 removal efficiency are in a good agreement with the experimental data from Kunio Kato (1999) et al.

Genetic Algorithm‐Based Variable Selection in Prediction of Hot Metal Desulfurization Kinetics

Sulfur is considered as one of the main impurities in hot metal and hot metal desulfurization is often carried out using injection of fine‐grade desulfurization reagent. The selection of variables used for predicting the course of hot metal desulphurization requires expert knowledge. However, it is difficult to model the complex interactions in the process and to evaluate a high number of possible variable subsets with manual variable selection techniques. As the amount of data gathered from the process increases, manual variable selection becomes too time‐consuming and might lead to a suboptimal prediction model. The objective of this work is to execute an automatic variable selection procedure for prediction of hot metal desulfurization based on an industrial scale data set. The variable selection problem is formulated as a constrained optimization problem, in which the objective function is formulated based on repeated leave‐multiple‐out cross‐validation. The implemented solution strategy is a binary‐coded genetic algorithm (GA). By making use of the developed model, the effect of the main production variables on the rate and efficiency of primary hot metal desulfurization is quantified. The variables related to properties of the reagent and the injection parameters were found to be of great importance.

Study of CO2injection on the desulfurization of low-titanium slag

A new idea that the low-titanium slag (LTS) used in the steelmaking process after CO2injection desulfurization is proposed in this paper. The CO2injection process mainly involves the grinding of low-titanium slag, mixing of slag and water, CO2injection, filtration, and then obtains the low sulfur and low titanium slag. The effects of cooling rates (water cooling, air cooling, crucible cooling, and furnace cooling) and CO2injection on the desulfurization of LTS were studied by both experimental and thermodynamic calculations. The results showed that sulfite and sulfate ions couldn’t be removed from LTS using this method, and the main removal substance in slag was sulfide ion S2−. The desulfurization mechanism with CO2injection was that the CO2injection reacted with H2O to form H2CO3, and then the H+disrupted from H2CO3reacted with the S2−in the slag to achieve desulfurization. During the desulfurization process, the desulfurization reaction was mainly determined by S2− + CO2(aq) + H2O (l) = CO32− + H2S(g) within the first 5 min, and then the main desulfurization reaction was S2− + 2CO2(aq) + 2H2O(l) = 2HCO3− + H2S(g). As the cooling rate decreasing, the desulfurization rate of LTS increased. The desulfurization effect of furnace-cooled slag is the highest in four kinds of slag. The desulfurization rate of furnace-cooled slag reaches 72.28%, which is 4.34, 1.75 and 1.15 times than that of water-cooled slag, air-cooled slag and crucible-cooled slag, respectively. The optimal rate of desulfurization is 80.0%.

Mechanism of Desulfurization from Liquid Iron by Hydrogen Plasma Arc Melting

In this study, desulfurization from liquid iron by Ar and (10 to 40 pct)H2 + Ar plasma arc melting (HPAM) was examined. The experimental results show that the rate of desulfurization increases as hydrogen is added proportionally to plasma gas. The thermodynamic analysis suggests that the interaction of activated atomic hydrogen and dissolved sulfur in liquid iron, $$ \left[ {\text{S}} \right] + 2{\text{H}} = {\text{H}}_{ 2} {\text{S}}, $$ could be taking place. The kinetic analysis confirms that the desulfurization from liquid iron obeys a first-order rate law.

Data-Driven Mathematical Modeling of the Effect of Particle Size Distribution on the Transitory Reaction Kinetics of Hot Metal Desulfurization

The aim of this work was to develop a prediction model for hot metal desulfurization. More specifically, the study aimed at finding a set of explanatory variables that are mandatory in prediction of the kinetics of the lime-based transitory desulfurization reaction and evolution of the sulfur content in the hot metal. The prediction models were built through multivariable analysis of process data and phenomena-based simulations. The model parameters for the suggested model types are identified by solving multivariable least-squares cost functions with suitable solution strategies. One conclusion we arrived at was that in order to accurately predict the rate of desulfurization, it is necessary to know the particle size distribution of the desulfurization reagent. It was also observed that a genetic algorithm can be successfully applied in numerical parameter identification of the proposed model type. It was found that even a very simplistic parameterized expression for the first-order rate constant provides more accurate prediction for the end content of sulfur compared to more complex models, if the data set applied for the modeling contains the adequate information.

Technological Innovations of Carbon Dioxide Injection in EAF-LF Steelmaking

In this study, the recent innovations and improvements in carbon dioxide (CO2) injection technologies for electric arc furnace (EAF)-ladle furnace (LF) steelmaking processes have been reviewed. The utilization of CO2 in the EAF-LF steelmaking process resulted in improved efficiency, purity and environmental impact. For example, coherent jets with CO2 and O2 mixed injection can reduce the amount of iron loss and dust generation, and submerged O2 and powder injection with CO2 in an EAF can increase the production efficiency and improve the dephosphorization and denitrification characteristics. Additionally, bottom-blowing CO2 in an EAF can strengthen molten bath stirring and improve nitrogen removal, while bottom-blowing CO2 in a LF can increase the rate of desulfurization and improve the removal of inclusions. Based on these innovations, a prospective process for the cyclic utilization of CO2 in the EAF-LF steelmaking process is introduced that is effective in mitigating greenhouse gas emissions from the steelmaking shop.

Electrochemical Desulfurization of Molten Steel with Molten Slag: Reaction Rate and Current Efficiency

It has been known that desulfurization of a molten steel using a molten slag can be enhanced by applying an electric field across the slag. In order to evaluate feasibility of the electrochemical desulfurization, a series of experiments were carried out using a high temperature reaction furnace under controlled electricity (constant current). A C-saturated molten steel including S was allowed to react with CaO-SiO2-Al2O3-MgO slags under various conditions: different currents (0, 0.05, 0.1, and 0.2 A) and reaction temperatures (1400, 1500, and 1600°C). Obtained experimental results were analyzed by employing kinetic rate equations including the Nernst-Planck equation. It was found that applying electric field enhanced the electrochemical desulfurization, both in final S content in the steel and in reaction rate. However, current efficiency for the desulfurization gradually decreased, due to deficient of S remained for the desulfurization in the molten steel. Electrochemical desulfurization under constant current was found to be effective at lower temperature, contrary to the normal desulfurization without the electric field. It is attributed to a fact that increasing temperature lowers resistivity of the slag, subsequently lowering electric potential difference exerted across the slag. Therefore, increasing reaction temperature would decrease the current efficiency for the electrochemical desulfurization, in terms of reaction rate and final extent of desulfurization.

Optimization of dispersed carbon nanoparticles synthesis for rapid desulfurization of liquid fuel

Stringent regulations and environmental concerns make the production of clean fuels with low sulfur content compulsory for the petroleum refining industry. Because of ease of operation without high energy consumption, the adsorption of sulfur compounds seems the most promising process. Central composite design was used to optimize parameters influencing the synthesis of dispersed carbon nanoparticles (CNPs), a new class of sorbents, in order to obtain an excellent adsorbent for desulfurization of liquid fuel. The optimized dispersed CNPs, which are immiscible in liquid fuel, can effectively adsorb different benzothiophenic compounds. Equilibrium adsorption was achieved within 2 min for benzothiophene, dibenzothiophene, and 4,6-dimethyldibenzothiophene with removal efficiency values of 75 %, 83 %, and 52 %, respectively. The rate of desulfurization by the prepared CNPs in the present work is seven times higher than the previously reported CNPs. Optimized CNPs were characterized by different techniques. Finally, the effect of the mass of CNPs on the removal efficiency was studied as well.

Effects of Modified Pyrolysis Tar on Gas Desulphurization Performance

The paper introduced effects of modified pyrolysis tar on flue gas desulfurization. This experiment selected the pyrolysis tar as the raw material, researched the effects on desulfurization performance under different modification solution, concentration, solid liquid ratio of pyrolysis tar and modified solution, calcination temperature and calcination time by 16 group orthogonal experiments. The results showed that: (1) The significance of five factors impact on the modified pyrolysis tar desulfurization performance in order was: types of the modified solution > modification solution concentration > calcination time > solid-liquid ratio > calcination temperature. (2) The modified effects of nitric acid and phosphoric acid were better. (3) The higher nitrate concentration, the better modified effect of pyrolysis tar. (4) The rate of desulfurization increased mainly associated with acidic groups on the surface of the pyrolysis tar, desulfurization performance get better along with the acidic groups increasing.