Numerical simulation and application experiment of the spontaneous combustion tendency of a coal stockpile covered with pulverized coal

2019 ◽  
Vol 98 (2) ◽  
pp. 616-624
Author(s):  
Ruizhi Chu ◽  
Minglei Wang ◽  
Xianliang Meng ◽  
Peng Liu ◽  
Zhenyi Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Spontaneous Combustion ◽  
Pulverized Coal

Effect Analysis of Nitrogen Injection on the Variation of “Oxidation Zone” in Coal Mine Gob Based on Numerical Simulation

2016 ◽  
Vol 9 (1) ◽  
pp. 47-54
Author(s):  
Jing Shen ◽  
Mingran Chang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Effect Analysis ◽  
Mine Fire ◽  
Nitrogen Injection ◽  
The Difference ◽  
Residual Coal

One of the main reasons for coal mine fire is spontaneous combustion of residual coal in gob. As the difference of compaction degree of coal and rock, the underground gob can be considered as a porous medium and divided into “three zones” in accordance with the criteria. The “three zones” are “heat dissipation zone”, “oxidation zone” and “choking zone”, respectively. Temperature programming experiments are taken and numerical simulation with obtained experimental data is utilized to analyze the distribution of “three zones” in this paper. Different width and depth of “oxidation zone” are obtained when the inlet air velocity is changed. As the nitrogen injection has inhibition effect on spontaneous combustion of residual coal in gob, nitrogen is injected into the gob. The widths of “oxidation zone” are compared before and after nitrogen injection. And ultimately the optimum location and volume of nitrogen injection are found out.

Numerical Simulation on Improving NOx Reduction Efficiency of SNCR by Regulating the 3-D Temperature Field in a Furnace

2013 ◽  
Vol 807-809 ◽  
pp. 1505-1513 ◽  
Author(s):  
Amir A.B. Musa ◽  
Xiong Wei Zeng ◽  
Qing Yan Fang ◽  
Huai Chun Zhou
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Removal Efficiency ◽  
Pulverized Coal ◽  
Measuring System ◽  
Optimum Temperature ◽  
Utility Boiler ◽  
Coal Particles ◽  
Injection Zone ◽  
Reduction Efficiency

The optimum temperature within the reagent injection zone is between 900 and 1150°C for the NOX reduction by SNCR (selective non-catalytic reduction) in coal-fired utility boiler furnaces. As the load and the fuel property changes, the temperature within the reagent injection zone will bias from the optimum range, which will reduces significantly the de-NOX efficiency, and consequently the applicability of SNCR technology. An idea to improve the NOX reduction efficiency of SNCR by regulating the 3-D temperature field in a furnace is proposed in this paper. In order to study the new method, Computational fluid dynamics (CFD) model of a 200 MW multi-fuel tangentially fired boiler have been developed using Fluent 6.3.26 to investigate the three-fuel combustion system of coal, blast furnace gas (BFG), and coke oven gas (COG) with an eddy-dissipation model for simulating the gas-phase combustion, and to examine the NOX reduction by SNCR using urea-water solution. The current CFD models have been validated by the experimental data obtained from the boiler for case study. The results show that, with the improved coal and air feed method, average residence time of coal particles increases 0.3s, burnout degree of pulverized coal increases 2%, the average temperature at the furnace nose decreases 61K from 1496K to 1435K, the NO emission at the exit (without SNCR) decreases 58 ppm from 528 to 470 ppm, the SNCR NO removal efficiency increases 10% from 36.1 to 46.1%. The numerical simulation results show that this combustion adjustment method based on 3-D temperature field reconstruction measuring system in a 200 MW multi-fuel tangentially fired utility boiler co-firing pulverized coal with BFG and COG is timely and effective to maintain the temperature of reagent injection zone at optimum temperature range and high NOX removal efficiency of SNCR.

scholarly journals Experimental study on controlled-release inhibitor foam for restraining spontaneous combustion of coal

2020 ◽  
Vol 38 (4) ◽  
pp. 1159-1177
Author(s):  
Xun Zhang ◽  
Jing Yang ◽  
Pengfei Xie ◽  
Hao Liu ◽  
Qiang Deng ◽  
...  
Keyword(s):  
Spontaneous Combustion ◽  
Hollow Spheres ◽  
Sodium Dodecyl ◽  
Pulverized Coal ◽  
Temperature Sensitive ◽  
Covered Area ◽  
Temperature Controlled ◽  
Specific Temperature ◽  
Spontaneous Combustion Of Coal ◽  
Low Efficiency

A new method is proposed based on temperature-controlled self-reaction to generate and release inhibitors in the form of foam at a specific temperature, which can overcome the disadvantages of short effective time and low efficiency in the inhibition of the spontaneous combustion of coal when inhibitors are released in advance, and greatly increase the action range of inhibitor through foam diffusion. The proposed temperature-controlled foaming system was prepared with hollow spheres as solution carriers, NaHCO3 and acetic acid as basic reactants, reaction-generated CO2 as foaming gas, sodium dodecyl sulfate and sodium carboxymethyl cellulose as foaming additives, NaCl, MgCl2 and CaCl2 as additives to enhance inhibition effect, and temperature sensitive paraffin as insulating material to generate and release inhibitor foam. The effects of releasing foam on restraining the spontaneous combustion of coal were studied based on the experimental analysis of the optimum ratio of reactants and additives, hollow sphere parameters, released temperature of the foam and variation rule of CO generated by coal oxidation. The obtained results showed that the released temperature of foam was 59–61°C and the covered area of pulverized coal by inhibitor foam was 12.9–13.9 times higher than when it was directly wetted by inhibitor solution. The total effects of inhibition and inerting were achieved after pulverized coal was wetted with inhibitor foam and the efficiency of restraining the spontaneous combustion of coal reached 88.51–97.06% when temperature was increased to 160°C.

scholarly journals Insulated Cable Temperature Calculation and Numerical Simulation

2018 ◽  
Vol 175 ◽  
pp. 03014
Author(s):  
Xin-jian Li ◽  
Jun Yang ◽  
Bing-qiang Yan ◽  
Xiao Zheng
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Spontaneous Combustion ◽  
Practical Significance ◽  
Constant Current ◽  
Sectional Area ◽  
Analysis Method ◽  
Insulation Layer ◽  
Insulating Layer ◽  
Temperature Calculation

A mathematical model of electrified insulated cable was established to calculate temperature of insulating layer. The insulating layer temperature is determined as a function of the current intensity, time, insulation layer thickness, etc. A widely used polyvinyl chloride (PVC) cable with sectional area of 4 mm2 was selected as example and its insulating layer temperature was simulated using ANSYS. The simulation revealed the evolution of insulating layer temperature with time, and also along radius after a certain time when the cable was applied with 40A and 60A constant current respectively. The analysis method has practical significance to prevent electrical fire and can be applied to analyze spontaneous combustion accident of insulated cable.

Numerical Simulation of High-Temperature Air Direct-Ignition of Pulverized Coal

2005 ◽  
Author(s):  
Z. Z. Kang ◽  
B. M. Sun ◽  
Y. H. Guo ◽  
W. Zhang ◽  
H. Q. Wei
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Temperature ◽  
Simulation Method ◽  
Pulverized Coal ◽  
Inlet Velocity ◽  
Operation Optimization ◽  
Structure Improvement ◽  
Simulation Results ◽  
Direct Ignition

Numerical simulation method is employed in this article to investigate various high-temperature air direct-ignition processes of pulverized coal (PC). Several important factors are analyzed, which are the inlet velocity of primary air flow, PC concentration and the velocity and temperature of high temperature air. The flow, combustion and heat transfer in high temperature air oil-free ignition burner can also be obtained from the simulation results, which are in accordance with the experimental data. The research provides guidance for structure improvement and operation optimization of burner.

Sign in / Sign up

Export Citation Format

Share Document