Abstract
Abstract Generally, adding a certain amount of an additive to pulverized coal can promote its combustion performance. In this paper, the effect of CaO on the combustion characteristics and kinetic behavior of semi-coke was studied by thermogravimetric (TG) analysis. The results show that adding proper amount of CaO can reduce the ignition temperature of semi-coke and increase the combustion rate of semi-coke; with the increase in CaO content, the combustion rate of semi-coke increases first and then decreases, and the results of TG analysis showed that optimal addition amount of CaO is 2 wt%. The apparent activation energy of CaO with different addition amounts of CaO was calculated by Coats–Redfern integration method. The apparent activation energy of semi-coke in the combustion reaction increases first and then decreases with the increase in CaO addition. The apparent activation energies of different samples at different conversion rates were calculated by Flynn–Wall–Ozawa integral method. It was found that the apparent activation energies of semi-coke during combustion reaction decreased with the increase in conversion.
Highlights
At present, it has become a routine technology for blast furnace ironmaking to replace coke with pulverized coal
To increase the amount of coal injected into the blast furnace and ensure that the coal powder is burned as much as possible inside the blast furnace, anthracite is generally mixed with bituminous coal for mixed injection [9,10]; this makes use of the high fixed carbon content and high calorific value of anthracite, and takes advantage of the low ignition point and good combustion characteristics of bituminous coal
Its pore structure is complex, its combustion performance is good, and its price is lower than anthracite; the use of semi-coke combined with bituminous coal can further reduce the cost of blast furnace coal injection
Summary
It has become a routine technology for blast furnace ironmaking to replace coke with pulverized coal. To reduce the cost of pig iron in blast furnace and reduce environmental pollution, increasing the amount of semi-coke in the mixed pulverized coal injection is an effective method. There are many studies on the co-combustion characteristics of semi-coke and other combustible substances, but there are few studies on the effect of combustion-supporting additives on the catalytic combustion performance of semi-coke Alkali metals such as Na and K have a good catalytic effect on combustion, after being added, they cause corrosion to the combustion equipment, which is not conducive to long-term use of the blast furnace [21,22]. The catalytic combustion of semi-coke was studied using CaO combustion aid, which has certain guiding significance for increasing the amount of semicoke in mixed injection coal powder
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