Sintering Flue Gas Desulfurization Research Articles

Mechanism and experimental study of desulfurizing agent based on Mn/Ce-Ca for sintering flue gas desulfurization (FGD)

A novel Mn/Ce-Ca-based desulfurizer was prepared by dipping-roasting method to improve the performance of single calcium hydroxide (Ca(OH)2) for sintering flue gas desulfurization (FGD) at 100–350 ℃. In this study, metal dopants iron oxide (Fe2O3) and magnesium oxide (MgO) are added to improve the microstructure of single Ca(OH)2 and enhance the utilization of active components. The experimental results on the fixed bed showed that the desulfurization performance got best when the ratio of Fe2O3 to MgO was 3:2, the dipping times of desulfurizer were two, the temperature was 350 ℃, and the oxygen content was 5%. Meanwhile, the effect of H2O content was also studied. Great desulfurization ability with a removal efficiency of 100%, sulfur capacity of 69.95 mg/g, and breakthrough time of 76 min was achieved by desulfurizer 3F2M–3MC-Ca. Even at a low temperature of 100 °C, the sulfur capacity of the desulfurizer is three times higher than that of single Ca(OH)2, confirming its advantages in low-temperature desulfurization. Moreover, the reaction mechanism is systematically elaborated via the kinetic, diffusion, and thermodynamic calculations, and the characterization of this desulfurizer is studied by XRD, SEM, BET, XPS, and ICP-OES. Results show that the addition of Mn/Ce significantly enhances the activity of the desulfurizer by providing abundant oxygen vacancies during the reduction reaction. The work presented here has profound implications for future studies of the low-temperature dry sintering flue gas desulfurization field. Finally, the potential application of this technology is discussed to demonstrate the industrial application value.

Subcritical hydrothermal oxidation of semi-dry ash from iron ore sintering flue gas desulfurization: Experimental and kinetic studies.

Realization of low temperature and high efficiency oxidation of CaSO3 is the key to solve the issue of ecological hazards caused by semi-dry sintering flue gas desulfurization ash. The subcritical hydrothermal technology was employed for the oxidation of CaSO3, achieving 89.83% of CaSO3 at 180°C, 2MPa for 120min with a solid-to-liquid ratio of 1:20. The macroscopic oxidation kinetics of CaSO3 in the subcritical hydrothermal reaction system was investigated. A mathematical model was established, incorporating the intrinsic reaction, CaSO3 dissolution, oxygen diffusion and CaSO4 precipitation. It was concluded that the macroscopic oxidation of CaSO3 was co-controlled by the oxygen diffusion and CaSO4 precipitation. Subcritical hydrothermal technology promises not only higher efficiency, but more importantly, potentially "one-step" preparation of CaSO4 whiskers, enabling cost-effective and high value-added resource utilization of the semi-dry FGD ash.

Structure Optimization Research Based on Numerical Simulation of Flow Field in Ammonia-Based Wet Sintering Flue Gas Desulfurization

Although more and more desulfurization equipment has been put into use in sintering plants, how to effectively remove sulfur dioxide from sintering flue gas in a desulfurization tower is still a great challenge in China. The desulfurization tower, as a critical part, needs further improvement and optimization. Therefore, based on the numerical simulation of the flow field of the ammonia-based wet desulfurization tower for sintering flue gas, ANSYS CFX is applied to conduct structural optimization research. Comparing the flow field distribution under different structure conditions, the results show that the flue gas distribution of the dual inlet tower is more uniform than that of the single inlet tower. The designed baffle not only effectively blocks the entry of the spray slurry, but also improves the flue gas distribution; the deflector with its simple structure, convenient operation, and stepped distribution installed in the entrance section can improve the uniformity of the flow field distribution. Based on the comprehensive analysis, these optimized structures are recommended in the design of an ammonia-based wet sintering flue gas desulfurization tower. This work not only develops a simulation of the desulfurization tower but also provides practical structures.

Subcritical Hydrothermal Oxidation of Semi-Dry Ash from Iron Ore Sintering Flue Gas Desulfurization: Experimental and Kinetic Studies

Subcritical Hydrothermal Oxidation of Semi-Dry Ash from Iron Ore Sintering Flue Gas Desulfurization: Experimental and Kinetic Studies

Numerical Simulation of a New Horizontal Spray Tower for Sintering Flue Gas Desulfurization

The flow rate and temperature of the flue gas from a sintering machine can fluctuate in a wide range; thus, the follow-up desulfurization facility should be operated stably and maintained on-line. A new type of horizontal spray tower, which can achieve high efficiency with low pressure loss and easy maintenance, was invented by the University of Science and Technology Beijing. A 3D multiphase computational fluid dynamics (CFD) model of the horizontal spray tower was constructed with Fluent software to study the internal flow field and the reaction of the horizontal spray tower. The standard k–ξ model and the Eulerian–Lagrangian model were adopted in this study. Results show that the flow field in the spray tower can be numerically simulated utilizing the CFD technology. The inlet angle exerts an important effect on the flue gas flow field of the horizontal tower. When the first-order efficiency and the economic indicators are taken into account, an inlet angle of 75° is recommended in the top inlet intake mode, whereas a 30° inlet angle performs the best in the side inlet intake mode. The spray configuration exerts an important influence. When the spray cone angle is 110° and the installation height is controlled at 0.8 m from the top surface, the smoke residence time is long, and the contact is sufficient. The results can provide theoretical support for the optimization of the structure of the spray tower.

Study on Application of the Evaluation Indicator System for the Third-party Environmental Pollution Control

A pilot evaluation indicator system was applied to environmental pollution governance. Four iron and steel enterprises introducing the third-party environmental pollution governance service were selected to carry out the evaluation and application, including sintering flue gas desulfurization and dust removal projects and waste water comprehensive treatment projects to which iron and steel enterprises pay high attention in “the 13th Five-Year Plan” period. Delphi Method was used to grade and quantify each indicator according to experience and determine the validity of scores. Radar charts for the four enterprises were formed based on the weights of Level-2 indicators for comprehensive evaluation and quantification of basic capability, facility operation, technical economy, environmental benefits and management level, and conclusions related to advantages and disadvantages of these enterprises were drawn. This research supplies a scientific method for evaluating the effect of environmental pollution control by third-party enterprises.

Study on optimum technological conditions of ore sintering flue gas desulfurization by using poor manganese

Orthogonal experiments were conducted to study the effect of each single factor on the desulfurization rate and leaching rate of Mn2+ to obtain improved process parameters. The results showed that the use of pyrolusite flue gas and the process method of by-product MnSO4 can not only effectively remove the sulfur in the gas, thereby controlling environmental pollution, but can also recover sulfur.

Ore sintering flue gas desulfurization and its resoureilization by using pyrolusite

Flue gas desulfurization (FGD) has been implemented for sulfur dioxide gas emission reduction by pyrolusite in iron ore sintering. However, the mechanism of SO2 reduction through FGD is still not fully clear. And in present work, the effects of operating conditions on desulfurization rate and Mn2+ leaching rate of pyrolusite were investigated. Six hours later, the desulfurization rate and Mn2+ leaching rate all can be higher than 70%. And a higher absorption temperature was good for desulfurization rate, while a middle temperature was good for Mn2+ leaching rate. A higher manganese ore granularity and SO2 concentration were good for desulfurization rate and Mn2+ leaching rate. However, a higher liquid-solid rate was only good for desulfurization rate, but Mn2+ leaching rate. The results demonstrate that the pyrolusite is a kind of very promising adsorbent in industrial flue gas desulfurization application due to its low cost and good desulfurization capacity.

Sintering flue gas desulfurization with different carbon materials modified by microwave irradiation

AbstractModification of metallurgical coke, biomass char and semi-coke was carried out using a microwave device with power of 450–850 W and irradiation time of 6–12 min. The desulfurization rates of three carbon materials before and after modification were tested. The effects of microwave power and irradiation time on the pore texture and surface chemical characteristics of the three carbon materials were examined by SEM, BET and Fourier transform infrared spectroscopy (FTIR). The results showed that the specific surface area, total pore volume and pore diameter of biomass char and semi-coke after irradiation decreased slightly. Noteworthily, the pore diameter turned small and the acidic functional groups on their surface decomposed, thereby the basicity of carbon surface increased by microwave modification. The optimal promotion of desulfurization rate of three carbon materials was semi-coke irradiated at 850 W for 9 min and the sulfur dioxide adsorption rate was up to 45%.

The efficient removal of thallium from sintering flue gas desulfurization wastewater in ferrous metallurgy using emulsion liquid membrane.

The removal of thallium ions in flue gas desulfurization wastewater from ferrous metallurgic industry was studied by emulsion liquid membrane (ELM) method using 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) as carrier, aviation kerosene (AK) as organic solvent, polyisobutylene succinimide (T154) as surfactant, polyisobutylene (PIB) as additive, and sulfuric acid as internal reagent. Some important influence parameters such as concentrations of carrier, surfactant and stripping agent, agitation speed, extraction time, volume ratios of feed solution to emulsion phase and internal phase to membrane phase, and their effects on the removal efficiency of Tl in the ELM process were investigated and optimized. Under the optimum operating conditions of 2% of carrier, 5% of surfactant, 0.5M of stripping agent, 350rpm of agitation speed, 12.5:1 of volume ratio of feed solution to emulsion phase, and 3:1 volume ratio of membrane to internal phase, the maximum extraction efficiency of thallium reached 99.76% within 15-min reaction time. The ICP-MS analysis indicated that the thallium concentration in treated wastewater was below 5μg/L and could meet the emission standard demand for industrial wastewater enacted by the local government of Hunan province of China. Meanwhile, the extraction of impurity ions calcium and magnesium in the ELM system was investigated. The result showed that an acidic environment would be in favor of the removal of Tl from calcium and magnesium contained in wastewater. Graphical abstract ᅟ.

Full-scale simulation of flow field in ammonia-based wet flue gas desulfurization double tower

With the increasingly strict environmental requirements, sintering flue gas desulfurization in double tower had been applied to improve desulfurization efficiency and reduce the “ammonia escape” and “aerosol” phenomena. In this work, the operating conditions of a sintering plant were simulated by ANSYS CFX and the flow fields without and with fluid spray of a full-scale ammonia-based wet flue gas desulfurization (WFGD) double tower were investigated. According to the results, the evaporating tower had a profound cooling effect on flue gas with spray. The gas flow distribution was non-uniform in evaporating tower, which needed further optimizations. The flow with spray was more uniform in both towers. The pressure drop mainly took place in absorption areas of desulfurization tower. The velocity of inlet region with spray was lower than that without spray in desulfurization tower. The temperature decreased along with the forward direction of gas flow due to the heat transfer with spray in desulfurization tower. The study provided useful data for further optimization in order to achieve high desulfurization efficiency.

Research Development of Resource Utilization of Sintering Flue Gas Calcium Based Desulfurization Byproduct

The sintering flue gas is one of the main pollution sources in the iron and steel industry, and the flue gas desulfurization has become an important aspect of air pollution control. In recent years, as a large number of sintering desulfurization equipments were applied, the byproduct has get more and more attention. This paper starts from the characteristics of sintering flue gas desulfurization process, analyzes the physical and chemical properties of different sintering flue gas desulfurization by-product, expounds the present situation of domestic and foreign desulfurization by-product resource utilization and the problems existing in the utilization process, and puts forward possible direction of the sintering flue gas desulfurization by-products with high added value, large amount of resource and no pollution.

3D simulation of sintering flue gas desulfurization and denitration in a bubbling gas absorbing tower

A full-scale three-dimensional Eulerian-Eulerian numerical model was established considering absorbing reactions in which the two-film theory model was adopted to describe the absorption process of SO2 and NOx. The established model was firstly verified by the industrial operation data of a 2×220m2 sintering flue gas desulfurization tower. Then, using the model, numerical simulations of simultaneous desulfurization and denitration process were carried out based on three different methods including spraying-inside tower oxidation absorption of the composited NaClO2/NaClO/Ca(OH)2 slurry, oxidation absorption of the composited NaClO2/NaClO/Ca(OH)2 slurry and bubble absorption of Ca(OH)2 slurry. Numerical results revealed that the first method, spraying-inside tower oxidation absorption of the composited NaClO2/NaClO/Ca(OH)2 slurry had the best performance on denitration without influencing on the desulfurization efficiency. The result was then further verified by an industrial scale test on a 2×220m2 sintering flue gas desulfurization tower.

Numerical simulation research of flow field in ammonia-based wet flue gas desulfurization tower

With the increasingly strict requirements of environmental protection, the removal of sulfur dioxide from a desulfurization tower has been a major target in China. Aimed at sintering flue gas desulfurization tower, ANSYS CFX software was used to simulate gas–liquid two-phase flow field in full-scale, in which the demist area was modeled as a porous medium regions, and the mesh independence confirmation was took into consideration. Comparing the flow field distribution under different spray levels, the flow field of the combination model of 2nd and 3rd spray level was relatively uniform, gas–liquid contact time was longer, which was beneficial to heat transfer; And the flow field distributions in tower for 3 layouts were not yet perfect for desulfurization; the pressure drop took place mainly in the absorber zone. This research could provide reference for the optimization and the select of spray levels with high desulfurization efficiency later.

Study on the Limestone-Gypsum Sintering Flue Gas Desulphurization Technology in Iron and Steel Plant

To date, limestone-gypsum has been the most widely used sintering flue gas desulfurization technology in China's steel industry. In order to demonstrate the application status, this paper stated the current desulfurization situation of Baosteel, Meishan Steel, Xiangtan Steel, Zhang steel. Process of limestone-gypsum obtained in these steel companies is playing an increasingly important role in sintering flue gas desulfurization, and a majority of these plants get a high desulfurization rate at more than 90%, which makes great contribution to the work of sulfur dioxide emissions. Besides, some problems of the desulfurization process in these plants are discussed and solutions are put forward to promote further development of the technology. For the prospects of the technology, it has been an inevitable trend to develop integration technology of desulfurization, denitrification and dioxin removal to meet requirements for energy saving work during the Twelfth Five-Year Plan. All these above presented in the paper will provide a basis in reality for the further development of this technology.

PH Control of Flue Gas Desulfurization in Sintering Process with Pyrolusite

The effect of rhodochrosite as the annexing agent of pH of pyrolusite slurry on desulfurization and manganese leaching was studied. The influence of the byproduct of sulfuric acid in the sintering flue gas desulfurization process on desulfurization and resource utilization of absorbent was also investigated. The results show that rhodochrosite produced the same effect as a pH buffering agent. High desulfurization and manganese leaching rates were maintained for a long period. This study showed the possibility of resource utilization of low-grade rhodochrosite.

Study on a New Technology of Flue Gas Desulfurization in Sintering Process

In this paper, a new technology of sintering flue gas desulfurization is proposed. The principle is that some kind of additives is introduced into feed mix, the additives decompose into NH3in sintering process during heating, the NH3reacts with SO2gas to form ammonium sulphate solid particles, the particles are captured as dust by ESP, so the removal of SO2in sintering flue gas is achieved. The study results show that the concentration of SO2in sintering flue gas decreases gradually with the increase of additive amount, when the specific quantity of additive is 3.02kg per ton mix, the decreasing rate of SO2is up to 81.33%(mass). Since sintering dust must be recycled as raw materials, in order to solve the problem of flue gas SO2concentration is gradually increasing, the approach of increasing the amount of additive can be taken, or the dust is separately treated for sulfur removal before being used as raw sintering material. The new approach of reducing SO2emission in sintering flue gas has advantages of low investment, small occupation area and low operation cost. Moreover, the additive is inexpensive and readily available, so sintering cost is not increased obviously.

Characteristics of fly ash from the dry flue gas desulfurization system for iron ore sintering plants

The characteristics of fly ash from the flue gas desulfurization (FGD) system are important for its reuse and are mainly depend on the desulfurization process. The physical and chemical properties of DSF ash, which refers to fly ash from the dry FGD system for the iron ore sintering process, were investigated. Its mineralogical contents were determined by X-ray diffraction and thermogravimetry analysis, and its micro-morphology was studied by scanning electric micrograph analysis. The results show that DSF ash has a higher CaO and SO3 content, and the main sulfur form is sulfite, with only a part of it oxidized to sulfate. The major minerals present in DSF ash are hannebachite, anhydrite, calcite and portlandite; a minor constituent is calcium chloride. The particles of DSF ash are irregular, fragmentary and small, and hannebachite grows on their surfaces. Particle size is affected by the FGD process, and the ash size from the maximized emission reduction of the sintering–FGD process is lower than that from the circulating fluidized bed–FGD process. The particle size distribution of DSF ash follows the Rosin–Rammler–Bennet equation.

Study of Dual-Alkali on Sintering Flue Gas Desulfurization

Combining with the characteristics and control methods of sintering flue gas, several common methods for flue gas desulfurization(FGD) and development trend of desulfurization technology were described in this paper. According to characteristics of sintering flue gas and selection principles, dual-alkali method was used in the FGD. Desulfurization process, basic principle and characteristics of the process were studied in detail. By contrast test, the effect of concentration of the desulfurization, flue gas flow and surface active agent on the desulfurization efficiency was investigated in detail through calculating the pH value of the solution before and after desulfurization reaction.

Experimental Investigation of Sintering Flue Gas Desulfurization with Steel Slag Using Dry CFB Method

SO2 Emission of sintering flue gas accounts for more than 70% of total SO2 emission of steel industry. The purpose of this paper was to use steel slag for desulfurization of sintering flue gas. Based on traditional circulating fluidized beds (CFB) for flue gas desulfurization (FGD), a new dry digestion CFB-FGD process was developed. The new process eliminated the traditional digestion procedure, and the functions of the reactor include preliminary dust collection, digestion and desulfurization. An pilot CFB installation with maximum flow rate of 8000 Nm3/h for flue gas desulfurization was established. The desulfurization effects of calces, converter slag and blast furnace slag were investigated under the following experimental conditions: temperature of inlet flue gas, 150 °C; temperature of outlet flue gas, 75 °C. Relative humidity, 13%; flue gas flow rate, 6800 Nm3/h; Ca/S ratio, 1.2. The results showed that all of the desulfurization agents had desulfurization capability and the desulfurization efficiency of calces was the best, followed by converter slag and blast furnace slag. The removal efficiency of steel slag ranged from 75% to 82%. Considering solid waste utilization, the application of steel slag in desulfurization using dry CFB has a promising future.