Alkali metal emissions in an early-stage pulverized-coal flame: DNS analysis of reacting layers and chemistry tabulation

Abstract Zhundong coal has been widely concerned because of its high alkali metal content, which brings great danger to the combustion of boiler. Therefore, it is extremely necessary to study the laws and characteristics of alkali metal influencing combustion in the burning process of zhundong coal. A gas-solid two-phase flow combustion model of pulverized coal containing NaCl was established by using Fluent software and FactSage software in a hot experimental combustion furnace. The influence of different NaCl content in pulverized coal on pulverized coal combustion process was discussed. The results show that with the increase of NaCl content in pulverized coal from 0 to 1% and 2%, the flame center temperature in the furnace increases about 80°C and 120°C under the same coal content, so it can be concluded that the increase of NaCl content can promote the combustion process of pulverized coal in the furnace. At the same time, it can be calculated that, with the increase of NaCl content, the flame range of the combustion region inside the furnace increases by 1/3. Because NaCl is decomposed by heat during combustion to help combustion, and the radiation heat transfer increases, the flame radiation range inside the furnace will increase.

Download Full-text

Effect of CO2 injection into blast furnace tuyeres on the pulverized coal combustion

High Temperature Materials and Processes ◽

10.1515/htmp-2021-0018 ◽

2021 ◽

Vol 40 (1) ◽

pp. 131-140

Author(s):

Juanjuan Jiang ◽

Rong Zhu ◽

Shengtao Qiu

Keyword(s):

Blast Furnace ◽

Coal Combustion ◽

Early Stage ◽

Three Dimensional ◽

Metallurgical Industry ◽

Pulverized Coal ◽

Co2 Injection ◽

Endothermic Effect ◽

Outlet Temperature ◽

Pulverized Coal Combustion

Abstract CO2 injection into blast furnace tuyeres is a new technology to utilize CO2, aiming at expanding the way of CO2 self-absorption in the metallurgical industry. The decisive factor of whether CO2 can be mixed into a blast-furnace hot blast and the proper mixing ratio is the effect of CO2 injection on pulverized coal burnout. To investigate the effect of CO2 injection into tuyeres on pulverized coal burnout, a three-dimensional mathematical model of pulverized coal flow and combustion in the lower part of the pulverized coal injection lance-blowpipe-tuyere-raceway was established, and the effect of CO2 injection into tuyeres on pulverized coal combustion rate and outlet temperature is analyzed. The numerical simulation results show that the delay of pulverized coal combustion in the early stage is caused by the endothermic effect of the reaction of CO2 with carbon, and the burnout of pulverized coal is increased in the later stage due to the oxidation of CO2.

Download Full-text

Alkali Metal Partitioning in Ash from Pulverized Coal Combustion

Combustion Science and Technology ◽

10.1080/00102209008951689 ◽

1990 ◽

Vol 74 (1-6) ◽

pp. 211-221 ◽

Cited By ~ 30

Author(s):

NEAL B. GALLAGHER ◽

LAWRENCE E. BOOL ◽

JOST O.L WENDT ◽

THOMAS W. PETERSON

Keyword(s):

Alkali Metal ◽

Coal Combustion ◽

Pulverized Coal ◽

Pulverized Coal Combustion ◽

Metal Partitioning

Download Full-text

Experimental study on gasification mechanism of unburned pulverized coal catalyzed by alkali metal vapor

Journal of the Energy Institute ◽

10.1016/j.joei.2019.05.012 ◽

2020 ◽

Vol 93 (2) ◽

pp. 679-694

Author(s):

Xiaojun Ning ◽

Zhengfu Peng ◽

Guangwei Wang ◽

Jianliang Zhang ◽

Tengfei Song

Keyword(s):

Experimental Study ◽

Alkali Metal ◽

Metal Vapor ◽

Pulverized Coal ◽

Alkali Metal Vapor

Download Full-text

The Deposit Formation Mechanism in Coal-Fired Rotary Kiln for Iron Ore Pellet Production: A Review

Crystals ◽

10.3390/cryst11080974 ◽

2021 ◽

Vol 11 (8) ◽

pp. 974

Author(s):

Shuai Wang ◽

Yufeng Guo ◽

Kuo Liu ◽

Zhuang Yang ◽

Yajing Liu ◽

...

Keyword(s):

Liquid Phase ◽

Alkali Metal ◽

Alkali Metals ◽

Iron Ore ◽

Coal Ash ◽

Pulverized Coal ◽

Efficient Production ◽

Material Base ◽

Deposit Formation ◽

Rotary Kilns

The deposit-forming problem is one of the main bottlenecks restricting the yield and production benefit of iron ore pellets produced by coal-fired rotary kilns. In order to implement measures to ensure the efficient production of pellets by coal-fired rotary kilns, the mechanism and influencing factors on the deposit formation were reviewed. The pellet powder and coal ash come together to form the material base of the deposit. Meanwhile, the local reducing atmosphere caused by the continued combustion of residual carbon increases the FeO content, resulting in the formation of low-melting-point silicates. Moreover, alkali metal elements in coal ash can also promote liquid phase formation to cause serious deposit aggregation problems. During high-temperature roasting, the liquid phase corrodes the surface of the refractory brick to form the initial deposit, whereafter, it binds the pellet powder and coal ash from the material layer, which causes the deposit to accumulate continuously. The deposit formation of coal-fired rotary kilns is the result of interaction between many factors, which includes the quality of the green pellets, the composition of coal ash, the combustion efficiency of pulverized coal, roasting temperature, FeO content and alkali metal input. Finally, it is recommended that some measures to mitigate deposit formation can be adopted, such as increasing the compression strength of preheated pellets, choosing high-quality raw materials with low alkali metals, improving the combustion of pulverized coal.

Download Full-text

Effects of Sewage Sludge on Combustion of Loading Alkali Metal Pulverized Coal

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.550-553.2315 ◽

2012 ◽

Vol 550-553 ◽

pp. 2315-2318

Author(s):

Li Hong Wei ◽

Na Zhang ◽

Tian Hua Yang ◽

Lei Wang

Keyword(s):

Sewage Sludge ◽

Alkali Metal ◽

Volatile Matter ◽

Pulverized Coal ◽

Combustion Characteristic ◽

Mixing Ratio ◽

Continuous Change ◽

Fixed Carbon ◽

Initial Release ◽

Sludge Ash

The effects of sewage sludge on combustion of loading alkali metal pulverized coal is carried out by thermogravimetric analysis (TGA). The result shows sewage sludge decreases initial release temperature and ignition temperature of volatile matter(VM) during the combustion of loading alkali metal pulverized coal. The combustion of fixed carbon in coal was promoted by the metal material in sludge when the sludge mixing ratio(SMA) was lower than 20% or inhibited because of the cover of sludge ash when SMA was higher than 40%. Comparison of stacking curves of sludge and measured curves of loading alkali metal coal, finds that: (1) there is no effect between sludge and coal, for the volatilization of water and small molecule substance, the combustion characteristic curves are superimposed in both experimental curves; (2) the co-combustion is interactional and interrestricted continuous change process, can't direct obtain from superimposition of curves, for the combustion of VM and fixed carbon. While SMA is lower than 20%, the samples have good combustion characteristic than pure coal.

Download Full-text

Risk management of energy efficiency projects in the industry - sample plant for injecting pulverized coal into the blast furnaces

Thermal Science ◽

10.2298/tsci150210094j ◽

2016 ◽

Vol 20 (1) ◽

pp. 315-325 ◽

Cited By ~ 1

Author(s):

Filip Jovanovic ◽

Ivana Beric ◽

Petar Jovanovic ◽

Aca Jovanovic

Keyword(s):

Energy Efficiency ◽

Risk Management ◽

Early Stage ◽

Pulverized Coal ◽

Production Costs ◽

Exhaust Emission ◽

Blast Furnaces ◽

Increase Energy Efficiency ◽

Increase Productivity ◽

Risk Management Methodology

This paper analyses the applicability of well-known risk management methodologies in energy efficiency projects in the industry. The possibilities of application of the selected risk management methodology are demonstrated within the project of the plants for injecting pulverized coal into blast furnaces nos. 1 and 2, implemented by the company US STEEL SERBIA d.o.o. in Smederevo. The aim of the project was to increase energy efficiency through the reduction of the quantity of coke, whose production requires large amounts of energy, reduction of harmful exhaust emission and increase productivity of blast furnaces through the reduction of production costs. The project was complex and had high costs, so that it was necessary to predict risk events and plan responses to identified risks at an early stage of implementation, in the course of the project design, in order to minimise losses and implement the project in accordance with the defined time and cost limitations.

Download Full-text