Injection Lance Research Articles

Numerical simulation of the effect of coaxial and cross-axis injection modes on pulverized coal combustion in the raceway of blast furnace tuyere

The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.

A water model study on mixing behaviour in a Kaldo furnace using acid–base neutralization decolourization method combined with RGB-based image analysis

Mixing time is usually used as an important parameter for quantifying the mixing performance of multiphase flow in a metallurgical bath. However, the topic of the mixing time of a Kaldo furnace for copper anode slime treatment has received little attention from scholars to date; this concept is important for guiding the optimization of high-efficiency smelting in the Kaldo furnace. In the present work, the mixing behaviour of gas-liquid two-phase flow in a Kaldo furnace was simulated using a scaled-down 1:4.5 water model fabricated from transparent acrylic plastic. A visualization technique and a quantitative characterization method for mixing performance in the Kaldo furnace—acid-base neutralization decolourization combined with RGB-based image analysis—were innovatively proposed. This approach can not only determine the global mixing level η¯(t) and track the frequency distribution of the local mixing performance ξk(t) of the fluid region during the mixing process but also quantify the mixing time. In addition, based on the proposed method and by using dimensional analysis, the effects of operating parameters (such as the gas flow rate Q, injection lance height h, rotation speed ω, liquid volume fraction φ, inclination angle θ, and liquid viscosity μl) on the mixing time of gas-liquid two-phase flow in the molten bath were discussed. On this basis, the empirical equation of the mixing time as a function of h, ω, φ, the modified Froude number (Fr'), μl and θ was established as the first quantitative relationship of the mixing time for the Kaldo furnace.

A method of designing an SNCR installation for small pulverized coal-fired boilers on the example of OP-50 boiler

Small pulverized coal-fired heating boilers are popular in heating and industrial applications. Recent changes in emissions limits forced interest in clean-up technologies dedicated for such a boilers, which previously were not included in regulations. The paper presents a method of designing an Selective Non Catalytic Reduction (SNCR) installation for small pulverized coal-fired boilers on the example of OP-50 boiler. Among main challenges during technology development and adjustment injection lances type, position, and operating parameters including reagent type and concentration can be enumerated. The designing process covered mainly following parts: object tests, temperature distribution determination (including balance calculations and computational fluid dynamics (CFD) modelling) leading to lances position determination, injection nozzles designing, installation tuning and calibration. Final measurements confirmed the ability of designed system to reduce NOx concentration in the flue gases below limit given in regulations.

Nonlinear dynamic verification of the boron injection lances for the Atucha-I Nuclear Power Plant

This work deals with the nonlinear transient dynamic verification of the boron injection lances for the Atucha-1 Pressurized Heavy Water Reactor backup shutdown system. The lances inside the moderator tank constitute the end part of the fast boron injection piping. The current dynamic verification of the lances is performed in the context of modifications in the piping and valve configuration for Atucha-I Long Term Operation (LTO). It is intended to ensure the structural integrity of the lances in the event of Loss of Coolant Accidents (LOCA) and spurious opening of level control valves (Spurious) scenarios. All boundary conditions have been provided by Nucleoeléctrica Argentina S.A. (NA-SA), and a 3-D numerical model of the lances was built and analyzed with the open-source suite Salome-Meca v2019 using the Code_Aster finite element solver. Results indicate that the displacement of the lances does not produce collisions with other reactor internals and that stresses on the lances and their fastening bolts are low enough to ensure the correct function of the system during LTO period.

Influence of different central nozzle diameters and powder injection rates on carbon powder mixed injection with shrouding supersonic oxygen jet (CMISSO) lance

ABSTRACT In order to improve the carbon powder utilization efficiency in electric arc furnace (EAF) steelmaking process, the carbon powder mixed injection with shrouding supersonic oxygen jet (CMISSO) lance was designed. In this study, the effects of different central nozzle diameters and powder injection rates on the dynamic characteristics of CMISSO lance are studied by numerical simulation, and the reliability of numerical simulation is verified by cold test. The results show that when the diameter of the central nozzle is 10, 15 and 20 mm, the mixing distance is 0.18, 0.28 and 0.30 m. Depicting that 10 mm centre nozzle diameter is the easiest to merge the central jet and the shrouding jet. The application of CMISSO injection lance can effectively make the powder get together. In addition, the larger the powder flow, the larger the powder distribution range and the lower the utilization efficiency.

Numerical Simulation on the Influence of Submerged Combustion on Splashing and Heat Transfer in TSL Furnace

Bath smelting technologies based on top submerged lance (TSL) injection have been widely used for pyrometallurgical metal production and solid waste treatment. In this work, a two-dimensional CFD simulation model of a pilot-scale 300 kg TSL furnace was established and applied to investigate the slag splashing phenomenon caused by submerged gas injection and combustion, with a special focus on the effect of submerged combustion on bubble formation, splash generation, splash distribution and heat transfer in the top space of the TSL furnace. The slag splash amount and distribution, and the temperature distribution characteristics inside the TSL furnace, especially under the influence of submerged combustion, were predicted, and influences of lance immersion depth and total injection gas flowrate on the splash behavior and heat transfer were investigated. As the lance immersion depth increases, more splashes are generated that distribute more evenly in the furnace top space and consequently heat transfer is enhanced. A larger injection gas flowrate generally increases the splash amount but the effect becomes weak when the injection gas flowrate exceeds a certain level, and there exists an appropriate range in injection gas flowrate for achieving the best heat transfer efficiency in TSL furnace.

Effects of temperature and load during hot impression behavior of Cr-Ni stainless steel

Austenitic Stainless steels are majorly used because of their high resistance to aqueous corrosion and high temperature properties. Some major applications of stainless steels at high temperatures include engine and exhaust components in aircrafts, recuperators in steel mills, and pulverized coal injection lances for blast furnaces. In all the above said applications, the components are constantly subjected to loads and high temperatures. This makes the study of their creep behavior very important to decide the life of the component. Cr-Ni stainless steel was used as a starting material, and hot impression creep test was performed on cylindrical samples of 10 mm height and 15 mm diameter for a dwell time of 150 min at two different loads of 84 and 98 MPa and at two different temperatures 450 and 500 °C. The time vs. indentation depth was plotted, and creep rate was calculated in each case. It was observed that with an increase in time, creep rate increased in the primary creep region and remained almost constant in the secondary creep region irrespective of temperature and load. The indentation depth and creep rate increased with an increase in load and temperature.

Interaction between a Liquid Surface and an Impinging Gas Jet

The water-air and Wood’s metal-air systems are modeled by means of Computational Fluid Dynamics to study the interaction between a liquid surface and an impinging air jet under the near field blowing conditions. The effect of the air jet velocity, the height of the injection lance, and the density of the liquid on the depth of the formed cavity is numerically studied. The CFD results of the cavity depth are compared with results previously reported by other authors. The emergence of the splashing phenomenon is predicted in terms of the critical velocity for each liquid-air system. Besides, the blowing number indicates that the drop generation rate is not significant for jet velocities below the critical velocity, and therefore neither the splashing is significant.

Stabilization mechanisms of CH4 premixed swirled flame enriched with a non-premixed hydrogen injection

High-fidelity Large Eddy Simulations (LES) are performed to study the effect of hydrogen injection on a lean turbulent CH4/Air premixed flame. An Analytically Reduced Chemistry (ARC) mechanism is used to achieve a detailed description of CH4/Air-H2 chemistry. First, a validation of this kinetic scheme against the detailed GRI-Mech 3.0 mechanism is presented considering both simplified and complex transport properties. When hydrogen is added to the mixture, large variations of the mixture Prandtl and of the N2 Schmidt numbers are observed depending on the local species concentrations, features that are missed by simplified models. LES is then applied to study the structure and stabilization mechanisms of a lean (ϕ = 0.8) premixed CH4/Air swirled flame enriched with hydrogen by using different transport modeling strategies. First, the fully premixed CH4/Air case is considered and results are found to validate the LES approach. In agreement with experiments, a classical V-shape flame is stabilized in the low-velocity region near the flame holder created by a central recirculation zone (CRZ). Then, hydrogen enrichment is achieved injecting 2% of the CH4 thermal power with a central fuel injection lance. Both premixed and diffusion flame branches are present in this case, impacting flame stabilization and flame angle. The flame root of the main premixed flame is stabilized by a diffusion flame kernel created by the injected hydrogen reacting with the oxygen in excess of the premixed stream. Moreover, the H2 consumed with the remaining oxygen in burnt gases leads to the formation of a second flame branch inside the CRZ which is responsible of an increase of the flame angle. Given the high concentration of hydrogen, an impact of the molecular transport models is observed on the flame lift-off height highlighting the importance of using complex transport properties in any LES involving hydrogen combustion.

Cold-Model Study on the Maximum Penetration Distance of the Injection Lance in a Kaldo Furnace

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of dore. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalurgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the dore and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η) was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

Lance Design for Argon Bubbling in Molten Steel

Three lance designs for argon bubbling in molten steel are presented. Bottom bubbling is considered too. Geometries considered are straight-shaped, T-shaped, and disk-shaped. The bubbling behavior of these lances is analyzed using Computational Fluid Dynamics, so transient three dimensional, isothermal, two-phase, numerical simulations were carried out. Using the numerical results, the bubble distribution and the open eye area are analyzed for the considered lance geometries. The plume volume is calculated from the open eye area and the lance immersion depth using geometrical considerations. Among the three lance designs considered, disk-shaped lance has the bigger plume volume and the smaller mixing time. As the injection lance is deeper immersed, the power stirring is increased and the mixing time is decreased.

A Straightforward Mathematical Model of Hot Metal Desulphurization

A straightforward kinetic model for the hot metal desulphurization process is presented. The model contains some of the most important parameters and variables that govern the process. The inputs, outputs and parameters of a desulphurization program employed at industry are discussed. The model is able to cope with different injection policies of desulphurizers such as mono- injection, co-injection or multi-injection. When compared to the rotary impeller method, results of this model shows that the weight of lime consumed in the lance injection method is lesser than that consumed in the rotary impeller method for the same conditions of the hot metal charge.

Influence of clogging of a T-shaped desulfurization lance on the flow field in a hot metal ladle

Lance injected desulphurization become ineffective when injection ports become obstructed. In this work, the difference of the flow fields between single and double hole injection was investigated by numerical simulations. When one of the openings in a T-shaped injection lance is blocked, a dead zone occurs in the ladle over approximately 1/4th of the volume, and there is not an active flow field on the surface of clogging side. To decrease clogging, industrial experiments examining different diameter lances were carried out. The results showed that clogging can be reduced by increasing the injection pressure and optimizing the injection hole diameter to be approximately 10 times the particle size of desulphurizer.

Experimental Study on Low Load Operation Range Extension by Autothermal On-Board Syngas Generation

Volatile renewable energy sources induce power supply fluctuations. These need to be compensated by flexible conventional power plants. Gas turbines in combined cycle power plants adjust the power output quickly but their turn-down ratio is limited by the slow reaction kinetics, which leads to CO and unburned hydrocarbon emissions. To extend the turn-down ratio, part of the fuel can be converted to syngas, which exhibits a higher reactivity. By an increasing fraction of syngas in the fuel, the reactivity of the mixture is increased and total fuel mass flow and the power output can be reduced. An autothermal on-board syngas generator in combination with two different burner concepts for natural gas (NG)/syngas mixtures was presented in a previous study (Baumgärtner, M. H., and Sattelmayer, T., 2017, “Low Load Operation Range Extension by Autothermal On-Board Syngas Generation,” ASME J. Eng. Gas Turbines Power, 140(4), p. 041505). The study at hand shows a mass-flow variation of the reforming process with mass flows, which allow for pure syngas combustion and further improvements of the two burner concepts which result in a more application-oriented operation. The first of the two burner concepts comprises a generic swirl stage with a central lance for syngas injection. Syngas is injected with swirl to avoid a negative impact on the total swirl intensity and nonswirled. The second concept includes a central swirl stage with an outer ring of jets. For this burner, syngas is injected in both stages to avoid NOx emissions from the swirl stage. Increased NOx emissions produced by NG combustion of the swirl pilot were reported in last year's paper. For both burners, combustion performance is analyzed by OH*-chemiluminescence and gaseous emissions. The lowest possible adiabatic flame temperature without a significant increase of CO emissions was 170–210 K lower for the syngas compared to low load pure NG combustion. This corresponds to a decrease of 15–20% in terms of thermal power.

Instrumenting full-scale Boron Injection Test Facility to support Atucha-2 NPP licensing

Abstract The Atucha-2 Pressurized Heavy Water Reactor is equipped with a back-up shutdown system based on the fast injection of boron into the moderator tank. Such system had initially been designed to cope with a 10%-area (0.1A) break Loss Of Coolant Accident (LOCA) scenario, but based on upgraded licensing requirements the design had to be revised and possibly improved against a double-ended guillotine (2A) break LOCA. In particular, the boron injection had to be proven fast enough to allow a timely shutdown of the reactor, even in the case of a failure of the primary shutdown system (control rods). A full-scale test facility was built for such “design validation” purpose, in the framework of a cooperation program between the University of Pisa – San Piero a Grado Nuclear Research Group (GRNSPG) and the utility Nucleoelectrica Argentina S.A. (NA-SA). A special instrumentation system, based on conductivity probes designed on purpose by the Helmholtz Zentrum Dresden-Rossendorf (HZDR), was adopted for the measurement of the injection delay, as well as for the monitoring of pressure at several key locations. Care was taken to reproduce the relevant NPP conditions as closely as possible to those expected on the basis of extensive safety analyses performed adopting a Best Estimate Plus Uncertainty (BEPU) approach. In this respect, not only the test facility is full-scale, but also the key components (such as the fast opening air valves, the boric acid tanks, the rupture device, the injection lance) were directly borrowed from the Atucha-2 NPP. This paper provides an overview of the test facility, with particular emphasis on the Authors’ contributions to its design, implementation and operation. Then, it highlights the final outcomes of the experimental campaign carried out by NA-SA, namely: allowing to improve the design of the boron injection system (especially as to some fluid–structure interaction issues) and – what was the main goal – demonstrating that the system’s performance is fast enough to assure a timely and safe shutdown of the reactor, thus contributing to the successful completion of the NPP licensing process.

The application of RANS CFD for design of SNCR technology for a pulverized coal-fired boiler

Abstract The article describes the technology of NOx emission abatement by SNCR method. The scope of research included CDF simulations as well as design and construction of the pilot plant and tests of NOx reduction by urea in the plant located in industrial pulverized-coal fired boiler. The key step of research was to determine the appropriate temperature window for the SNCR process. The proposed solution of the location of injection lances in the combustion chamber enabled to achieve over a 30% reduction of NOx. It is possible to achieve higher effectiveness of the proposed SNCR technology and meet the required emission standards via providing prior reduction of NOx to the level of 350 mg/um3 using the primary methods.

Effect of gas rate and position of powder injection on RH refining process using numerical simulation

In this study, the gas–liquid two phase flow behavior in the vacuum vessel during the Rheinstahl-Heraeus (RH) refining process was investigated to improve the refining effect. Special attention is paid to investigate double powder injection lances system which is used to improve the refining efficiency during RH refining process. The melt flow behavior, circulation flow rate and mean residence time of the tracers with different powder injection gas flow rates and different configurations of the double powder injection lances are simulated using three-dimension numerical model based on Eulerian-Eulerian approach. The results show that, with the increasing gas flow rate of the power injection, the circulating flow rate and the mean residence time of tracer increases. It is also noted that the mean residence time of tracer varies with the different positions of the powder injection lances. It is found that there is an optimum location of the positions of the powder injection lances corresponding to the increasing of the residence time of powder and can improve the refining effect.

Optimization of Desulphurization Process using Lance Injection in Molten Iron

Optimization of Desulphurization Process using Lance Injection in Molten Iron

高炉微粉炭多量吹込み用収束−拡大型分散強化ランスの開発

To achieve a high rate injection of pulverized coal into a blast furnace, it is so important to increase a combustion efficiency of pulverized coal. Enhancement of particle dispersion is one of the measures to increase combustion efficiency by accelerating oxygen-coal particle mixture in blowpipe to tuyere region. To realize this, it is found that convergent - divergent injection lance designed on the basis of fluid dynamics has superior characteristics. Divergence angle of the lance is optimized as the maximum angle free from the flow separation phenomenon in the boundary layer and convergence angle of the lance is optimized considering the inertia of coal particle in the gas-solid two phase flow. Optimum divergence angle and convergence angle is found to be 7 and 5 degrees respectively. Direct observation results by offline apparatus, hot model experiments and even in the actual blast furnace proves that dispersion of pulverized coal particles is enhanced considerably.

Physical simulation of converter steelmaking with powder injection

A water model of top and bottom blown converter with top lance powder injection and bottom tuyere powder injection was established to investigate the powder injection. The results show that the powder penetration ratio under the condition of top lance injection is greater than that under the condition of bottom tuyere powder injection. In both cases, the powder penetration ratio increases with the increase of solid/gas ratio and powder particle size. Powder uniform dispersion time with top lance powder injection is longer than that with bottom tuyere powder injection. Top lance powder injection, lance height of 258 mm, bottom blowing rate of 1·96 Nm3 h−1 and powder particle size of 0·212–0·380 mm are suggested as the optimum powder injection operation under the experimental condition. The corresponding optimum operation for prototype is top lance powder injection with lance height of 1550 mm, powder size of 1–5 mm and bottom blowing rate of 450 Nm3 h−1.