Results showed that the ignitability, the combustion property, and the burnout were largely improved when added oxygen was used, especially for small particles, the influence of oxygen on the bituminous coal was greater than the lignite and the anthracite, and the suitable O2 concentration for the ignition of pulverized coal flow should be controlled below 40%. Pulverized coal combustion in mixture of oxygen and recycled flue gasses, known as oxy-fuel combustion, is considered as one of the several possible alternatives to conventional pulverized coal combustion. By continuing you agree to the use of cookies. However, increasing oxygen mole fraction decreased the ignition temperature for all coals. The use of a captive technique for direct measurement of ignition temperatures of pulverized coal and char particles is described. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Ignition temperature of pulverized coal particles: Experimental techniques and coal-related influences. Two experimental techniques—the first using a pulse of coal and the second, a continuous flow of coal and air in near stoichiometric proportions—are shown to give similar gas temperatures for the onset of flashing. Pulverized coal combustion was investigated for bituminous coal and anthracite at different temperatures (973K and 1173K) in a horizontal fixed-bed reactor test system using computational fluid dynamics (CFD) software. The effects of radiant heat transfer were strong for intermediate-size particles (37–74 μm). Experimental investigation on ignition modes of pulverized coal clouds relating to the dust concentration is performed in a drop tube furnace. However, little oxygen is consumed during this initial visual event. Fuel 2010 , 89 (3) , 743-751. Then, the effects of ambient temperature, oxygen mole fraction and coal rank on the characteristic ignition delay are examined. 5—Concept of In-flame NOx Reduction. However, little oxygen is consumed during this initial visual event. Anthracite coal has also been widely used in hand-fired furnaces. The measurements were made in air on particles of 60 μm mean size. The concentration of the pulverized coal is a critical factor in enhancing ignition. content and relatively high ignition temperature. : +86 -2787545526; fax: . 12. Auto Ignition Temperature table that shows the minimum temperature required to ignite a gas or vapor in air without a spark or flame being present. Ignition temperature of pulverized coal particles: experimental techniques and coal-related influences. Ignition behavior of pulverized coals in lower oxygen content ... devolatilization of bituminous and subbituminous coal at a gas temperature of 1700K over a range of 12~36% O2in both N2 and CO2diluent gases.Zhang(2010)employed the high speed camera to capture the particle imagesin the Corresponding author. In this paper, one oil-free ignition technique is studied for oil-saving, in which high temperature air is used to ignite PC. The use of a captive technique for direct measurement of ignition temperatures of pulverized coal and char particles is described. pulverized coal-fired (PC-fired) boilers, the fuel is pulverized to the consistency of talcum powder (i.e., at least 70 percent of the particles will pass through a 200-mesh sieve) and pneumatically injected through the burners into the furnace. Pulverized coal producing processes are widely used in thermal power stations, cement and iron-smelting industry. Need to speak to someone? 2 Many accidents and protection techniques have been reported by former investigations [1-3]. This paper reports on combustion characteristics of pulverized coal particles at particle temperatures over 1800{degrees} C an oxygen concentration of 40%-80% that were investigated using a high-temperature drop furnace. By continuing you agree to the use of cookies. E-mail address:zliu@mail.hust.edu.cn. coals to burners, ambient-temperature air that has not been preheated must be used to prevent self ignition. Laboratory measurements of the visual and combustion sequences during the ignition of pulverized coals, chars, and petroleum coke are reported. 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. 8 coals to determine the relation of the rate of burning of pulverized fuels and of the radiation from their flames, to the type of coal and the fineness of … These two temperatures appear to be better indicators of the ignitability of pulverized coals in combustors than the first flash temperature. At a gas temperature, about 100°–200°C higher than the first flash temperature, the oxygen consumption is seen to increase rapidly and this is accompanied by the rapid generation of NOx. This characteristic temperature decreases with an increase in the ambient oxygen concentration but appears to be independent of particle size. satyendra; October 4, 2018; 0 Comments ; ash, blast furnace, coal, Combustibility, Explosibility, Grindability, HGI, Ignition point, moisture, PCI, Rank, reactivity, Tuyere, VM,; Coal for Pulverized Coal Injection in Blast Furnace. Then, the effects of ambient temperature, oxygen mole fraction and coal rank on the characteristic ignition delay are examined. However, when using higher rank coal (coal C), the ignition was significantly prolonged with decreasing the temperature from 1300 K to 1100 K or with increasing the particle size to above 150 μm. Normally, the traditional coal process systems use ball mills to pulverize coal. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Ignition temperature of pulverized coal particles: Experimental techniques and coal-related influences. The different ignition behaviors under different oxygen fraction suggest that the turbulence effect is sensitive to coal ignition modes. Ignition temperature was examined analytically by using a modified distributed activation energy model for pyrolysis. 2004;29(5):611–13. The ignition delay of coal particles was prolonged in the slow-heating O. The ignition behavior of coal particles was studied through an enhanced numerical model, combined with experimental investigations in a visual drop tube furnace in the temperature range of 1100–1300 K. The devolatilization and the combustion of volatile and char during combustion of single coal particle were thoroughly studied. It is found to be very close to the flame formation temperature. The physical process of ignition of pulverized coal is simplified and analyzed. The results show that the ignition temperature of pulverized coal particles at 21%O2/79%CO2 environment is higher from 62°C to 130°C than that at air (21%O2/79%N2) environment for … An experimental study on ignition and combustion of single coal particles under different O 2 concentrations was conducted at both normal (1-g) and microgravity (μ-g) in the first time. Wujun F, Dong L. Experimental study on high-temperature air ignition of pulverized coal. The high temperature sufficed to promote NO x formation. For example, a thermogravimetric technique ... Pulverized coals are ignited by the high temperature gas in the recirculation flow. 1990;79:569–78. The coal + air mixture at the ignition point is flammable. Fig 1 Pulverized coal combustion and gas composition in raceway. Three coal types of … These two temperatures appear to be better indicators of the ignitability of pulverized coals in combustors than the first flash temperature. In China, over 70 percent of the power production feeds on thermal power plants running with pulverized coal (PC) fired boilers. Coal particles were ignited by injecting high temperature gas flow. The flame formation temperature, Tys and the rapid oxygen consumption temperature, TO2 appear to be good indicators of the ignitability IGNITION TEMPERATURE FOR COAL PARTICLES 339 of pulverized coals in practical combustion equip- ment. At the same time, the flow rate of the air must be as small as possible to prevent reductions in boiler efficiency. Two coals of different rank (sub-bituminous and lignite), two particle size fractions (180-212 μm and 106-125 μm) at two furnace temperatures (1550 K and 1800 K), with oxygen concentration in the ambient gas varying from 10% to 50% by volume were used for the experiments. Two experimental techniques—the first using a pulse of coal and the second, a continuous flow of coal and air in near stoichiometric proportions—are shown to give similar gas temperatures for the onset of flashing. The results demonstrate that the ignition delay time and burnout time are less than 10 and 50 ms, respectively, in the case of combustion under a high-temperature/high-oxygen … Pyrolysis of large particles was delayed, but accelerated after ignition by radiant heat transfer from coal flames.