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Effect of COG injection area ratio on heat front speed and flame front speed. (Online version in color.)
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Coke oven gas (COG) injection is believed to improve the quality and yield of sinter in iron ore sintering process. A mathematical model is developed to simulate the sintering process with COG injection, particularly focusing on predicting the quality and yield of sinter. The model is validated by comparing the model predictions with sintering pot...
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Context 1
... effects of COG injection area on flame front and heat front are shown in Fig. 17, where the injection quantity is 0.5% and the injection location is from 60 s after ignition. It can be observed from the figure that, although the magnitude of change is not big, both the flame front speed and heat front speed decrease with the increase of COG injection area. The two fronts attain their best speed consistency when the ...
Context 2
... effects of COG injection area on flame front and heat front are shown in Fig. 17, where the injection quantity is 0.5% and the injection location is from 60 s after ignition. It can be observed from the figure that, although the magnitude of change is not big, both the flame front speed and heat front speed decrease with the increase of COG injection area. The two fronts attain their best speed consistency when the ...
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This research put forwards a stepwise parameter optimization approach based on maximum satisfaction aiming at the characteristics of multi-process control indices and cascading in iron ore sintering process. Given the sintering process involves multiple quality indices and the demand of reducing cost of first proportioning and the consumption of co...
Citations
... Wang et al. [9] reported a flue gas recycling sintering technology and studied the effects of flue gas recycling on temperature distribution in the sintering bed. Ni et al. [10] studied coke oven gas (COG) injection technology on a sintering bed surface. The results of their study indicated that the temperature evolution curves of the sintering bed were different from those of CS. ...
... The pressure outlet and velocity inlet were used here. The heat loss through the sintering machine wall was obtained based on other studies [10,26]. ...
... These changes can help in addressing the heat deficiency in the upper bed of the CS technology. (3) Cooling rate and melt quantity index Ni et al. [10], Loo et al. [31], Zhang [32], and Liu et al. [33] proved that the MQI is directly proportional to the tumbler strength of a fired sinter. Based on the temperature distribution shown in Figure 11, the corresponding CR and MQI values at different bed heights were obtained, as shown in Figure 12. ...
The fuel segregation distribution sintering process, with a high fuel dosage in upper layer and a low fuel dosage in bottom layer of the sintering bed, was studied to handle uneven heat distribution problems in the conventional iron ore sintering process. A mathematical simulation method was adopted to contrastively study the fuel segregation distribution sintering process and the conventional iron ore sintering process. The accuracy of the model was verified through the sintering experiments. In addition, different heights of the upper and bottom sintering beds were discussed to assess the fuel segregation distribution sintering technology. In contrast to the conventional iron ore sintering process, the temperature evolution in the sintering bed using the fuel segregation distribution sintering technology tended to be more reasonable and the heat accumulation in the upper bed increased, which meant that the melt quantity index increased from 2178 to 2387 K·min, and cooling rate decreased from 360 to 199 K·min−1. The drawbacks of the conventional iron ore sintering process, such as the heat shortage in upper bed and excess heat in lower bed, were therefore improved, which was also proven to promote the sinter quality.
... With growing interest in this topic, sinter models considering gaseous fuel injection are developed. Ni et al. investigated the influence of coke oven gas injection on specific positions of the sinter strand and validated the simulation results with sinter pot tests [26]. Tsioutsios et al. developed a non-stationary 1D model for parameter studies for supporting sinter pot experiments. ...
The use of sinter influences hot metal production substantially and significantly affects an integrated steel mill’s total emissions. Sintering of iron ores is an enormous energy-intensive and resources consuming process. Introducing a selective waste gas recirculation (SWGR) to the sintering process reduces the energy consumption, stack gas volume flow, and sulfur dioxide emissions of an iron sinter production. Simulating this complex process in flowsheet simulations of integrated iron and steelworks is a fast and cost-effective opportunity to validate new operation settings. The implementation of a sinter plant in gPROMS ModelBuilder®characterizes the sintering processes by three main sub-models. A burner model describes the gas combustion, a black-box model consider the main sintering processes, and a wind box model divides the total off-gas into a recycle gas and a stack gas. A specific temperature polynomial represents the temperature distribution across the wind boxes to allow detailed investigations on SWGR in complex flowsheet simulations. Implementing SWGR to the sintering process, the model shows a reduction of coke consumption, stack gas flow rate, and sulfur dioxide emissions by 11%, 27%, and 27%, respectively. In the SWGR scenario, the utilization rate of carbon monoxide increases and less coke is consumed. The chlorine emissions of the sintering process differ with and without SWGR insignificantly.
... It involves granulating the mixed ore, flux, and solid fuel, distributing the granulated materials in the bed, igniting the solid fuels (coke breeze), sintering the iron-bearing materials via the combustion of solid fuel in a grate with air suction beneath the grate, and finally cooling the fired sinter (Matsumura et al., 2005;Loo et al., 1998;Shen et al., 2006). In the sintering process, the consumption of solid fuel such as coke breeze and coal accounts for >85% of the total energy consumption (Ni et al., 2020), resulting in a large amount of CO 2 emissions. Moreover, the pollutants produced in the sintering process such as CO, SO 2 , and NO x , present a serious environmental challenge owing to the extensive use of coke/coal (Fan et al., 2013). ...
... Combustible gas-particularly hydrogen-bearing gaseous fuel-has been developed as an alternative candidate to replace coke/coal (Oyama et al., 2011a,b). Ni et al. (2020) and Castro et al. (2012) investigated the effects of combustible gas injection on the sintering process and sinter quality via mathematical modelling. They selected coke oven gas (COG) as a gas fuel. ...
... T 1 : solidus temperature of the melting phase; T 2 : liquidus temperature of the melting phase. T 1 -the solidus temperature of the raw material-is set as 1373 K in accordance with a previous work (Ni et al., 2020). T 2 is set as 1673 K in accordance with the CaO-Fe 2 O 3 phase diagram (Zhou et al., 2012). ...
With the objectives of reducing CO2 emissions and applying hydrogen-enriched gas in the iron ore sintering process, a mathematical model was developed to simulate the natural gas (NG) injection in the sintering process. The accuracy of the model was verified via sinter pot tests. Additionally, an environmental assessment of CO2 mitigation was performed. Moreover, the effects of the injection quantity, location, and intensity on the sintering process were examined. Sintering process parameters were adopted to quantitatively assess the NG injection technology. The results indicated that this technology can reduce the CO2 emissions. The CO2 mitigation dosage is 11.75 kg/ton sinters when 15% solid fuel is replaced with NG. The melting zone thickness (MZT) and binding liquid phase amount in the upper sintering bed are gradually improved with NG injection quantity increased gradually, which indicates that the holding time of the high temperature zone in the upper bed is prolonged. Furthermore, the injection locations and intensities affect the sintering process. Earlier injection allows more heat storage and forms more binding liquid phase in the upper bed. Low intensity injection reduces the MZT of the sintering bed and negatively affects the sintering process.
... Also, controlling the temperature condition of HRG is much easier during tuyere injection than during shaft injection, because during tuyere injection, the gas naturally goes to the raceway. Therefore, tuyere injection of various gaseous fuel such as H 2 [23], coke oven gas [24], and natural gas [6,25] has been studied. However, tuyere injection can severely decrease the raceway adiabatic flame temperature (RAFT) when a large amount of HRG is injected. ...
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Our goal is to find a strategy to reduce coke use during operation of a blast furnace (BF). This study focuses on the techno-economic and environmental impact analysis of tuyere injection of hot reducing gas (HRG) from low-rank coal (LRC) gasification in the BF. LRC gasification by entrained-flow gasifier is introduced to make gaseous fuel, and the cleaning process of the raw syngas is implemented using Aspen Plus V10. The effects of HRG injection are evaluated using a BF model derived from the Rist operating diagram. Integrated results from raw fuel to the BF were analyzed considering economic, energy, and environmental aspects. By injecting rich syngas (>95 vol. %) into the BF at 1150 K, coke replacement ratio is estimated to be 0.354 kg/Nm³ without adverse impact on the BF. The most sensitive economic factor is coke price. The energy efficiency of raw syngas cleaning process, relative energy intensity of LRC, gas utilization ratio are 57.5%, 90.6%, and 50.0% respectively. Utilization of HRG can reduce CO2 emission by 21.88 ktCO2/yr compared to the reference BF operation.
... [1][2][3][4][5] Reduction shaft furnace is an effective process to produce DRI, and it's developed worldwide, including Midrex, HYL, upper part of COREX etc. [6][7][8][9][10][11][12] Many research related to the reduction shaft furnace had been reported. [13][14][15][16][17][18][19][20][21][22][23][24][25] For example, Kato et al. 13) aimed to reduce CO 2 emission from industrial energy processes, investigated the application of carbon recycling ironmaking system in a shaft furnace. They proposed the feasibility of application of CO/CO 2 mixture gas in shaft furnace, and give the guidelines about top gas recycling for our work. ...
... Zuo et al. 18) investigated the reduction kinetics of iron oxide pellets with H 2 and CO mixtures. The gas compositions in literatures [17][18][19][20] are between the Coke Oven Gas (COG) and reformed COG. Zhou et al. 21) investigated the solid flow by discrete element method, including flow patterns, descending velocity, residence time distribution, interactive force etc. ...
Reduction shaft furnace is an effective process to produce Direct Reduced Iron (DRI), in which natural gas is used as reducing agent and heat source. Recently, in some countries lacking natural gas resources, Coke Oven Gas (COG) was proposed to be used in shaft furnace process instead of natural gas. In the present work, the effect of COG consumption on the yield of metallic Fe in shaft furnace was thermodynamically calculated. Both the chemical equilibrium and heat balance were considered. The main findings include, in shaft furnace process, the COG consumption as heat source is more than that as reducing agent. In the case of directly supplying reformed COG, the yield of metallic Fe decreases with increasing formation temperature of metallic Fe. For a coke oven with capacity of 600000 tons, as the formation temperature are 850°C and 900°C, the corresponding annual yields of shaft furnace are 253.58 × 10³ tons/year and 249.48 × 10³ tons/year. In the case of ZR technology followed by supplying extra COG, the yield of metallic Fe first increases and then decreases, and there is a peak value. For a coke oven with capacity of 600000 tons, as the formation temperature are 845°C and 900°C, the corresponding annual yields of shaft furnace are 283.44 × 10³ tons/year (maximum value) and 278.38 × 10³ tons/year. The findings from this work may provide guidelines for choosing optimal parameters for an actual shaft furnace process.
Flow chart of reduction shaft furnace process (O2 pyrolysis). Fullsize Image
A high-temperature gas-solid reaction device was used to simulate the gasification of coke in a hydrogen-rich blast furnace, with the gasification reaction of water/anhydrous bulk cokes studied. CO2 and H2O effects on coke gasification kinetics were analyzed in CO2-N2-H2O and CO2-N2 with the experimental temperature of 1173–1523 K, the CO2 content of 15–60%, and the H2O content of 15%. Compared with those of CO2-N2, the gasification reaction rate and carbon conversion rate of cokes in the CO2-N2-H2O mixture were significantly higher. Carbon conversion rates of the CO2-N2-H2O mixture at different temperatures were about 30% higher than those of CO2-N2 on average, and the gasification reaction rate was about 50% higher on average. There were two temperature regions for gasifying cokes in CO2-N2-H2O and CO2-N2 mixtures. At 1,273 K, the gasification reaction is transformed into diffusion control, which is from chemical reaction control. The aggravation of coke gasification by H2O generated after hydrogen reduction of iron ores was mainly reflected at the lower temperature. Besides, the kinetic model analysis showed that random pore model was optimal in describing the gasification reaction of cokes in CO2-N2-H2O and CO2-N2, and the addition of H2O improved the gasification reaction’s activation energy.
