【正文】 ion chamber of a furnace bringing it to its operating , oil is delivered under high pressure by an oilgun with a delivery capacity of about 1 tonne/h. Therefore, in the initial firingup process of a bituminous coalfired 300 MWe utility boiler, about 100 tonnes of fuel oil would be consumed. Concerns over increasing economic costs in pulverized coalfired power stations arising from oil consumed in the firingup process and partialload operations has spurred interest in developing oilfree and tinyoil ignition burners. Various investigators have reported studies of oilfree ignition burners. Masaya et al. studied the stabilization of pulverized coal bustion using a plasmaassisted burner, while Kanilo et al. investigated the ignition and bustion of pulverized coal using a microwaveassisted burner. In China, Zhang et al. described their application of plasma ignition technology in bituminous coalfired boilers. However, for such burners, two main problems arise: difficulties in extending the capacity of the burner and the frequent maintenance required during operation. Li et al. investigated inductionheating ignition of a pulverized coal stream. Inductionheating can supply a reliable convenient source of energy to ignite the pulverized coal stream, but this technology has not been previously reported to have been used in any utility boiler.An alternative tinyoil ignition burner has been developed and tinyoil ignition, centrally fuelrich burners proposed (see Fig. 1). The burner features two oilguns arranged in the central pipe and the firingup process is summarized as follows. Atomized oil from one oilgun, called the main oilgun, ignites and burns in an adiabatic chamber. Subsequently, an oil flame ignites the atomized oil from the other oilgun, called the auxiliary oilgun. Cone separators are installed in the primary air–coal mixture duct to concentrate the pulverized coal into the central zone of the burner. The fuelrich primary air–coal mixture passes into the first bustion chamber whereby the fuelrich primary air–coal mixture is ignited by a hightemperature oil flame formed by both main and auxiliary oilguns. Next, the burning pulverized coal and oil flame from the first bustion chamber is directed into the second bustion chamber where the coal is ignited. After the boiler has been firedup, both main and auxiliary oilguns are then shut down and the burner switches operations to being a centrally fuelrich burner . Characterized by high bustion efficiency and low NOx emission. The influence of coalfeed rates on the bituminous coal ignition in the fullscale tinyoil ignition burner was investigated.2. Experimental setupFig. 1 shows the tinyoil ignition apparatus. The ignition burner was identical to the burner that had been used in an 800MWe utility boiler and its operation is briefly described as follows. The feeder supplies pulverized coal by primary air from the blower. The pulverized coal is then carried to the tinyoil ignition burner by primary air. Oil is drawn from the oil tank and sent to the main and auxiliary oilguns atomizing the oil mechanically and by air. Although pressed air enters the oilguns, a small fraction is also consumed in oil bustion, the main body of which is supplied by another blower. The pulverized coal is ignited in the primary air duct. In the experimental setup there was no separation into inner and outer secondary air.All gas temperatures were measured at the center of the burner as well as the exits of the first and the second bustion chambers. Ash samples were sampled at the exit of the tinyoil ignition burner. Gases were sampled using a watercooled stainless steel probe and analyzed online on a Testo 350M instrument [5]. The probe, consisting primarily of a waterinlet pipe, wateroutlet pipe, sampling tube, outer pipe and supporting ponents, was bracketmountedat the exit of the burner. A sample of the hightemperature gas is collected in the sampling tube and cooled by high pressure cool water delivered through the waterinlet pipe cooling the sampling tube and after heat change flows out via the wateroutlet pipe. A water pump provided continuous water circulation. When gas enters the sampling tube, temperatures decease rapidly and the pulverized coal stops burning. Samples are drawn up by a pump through filtrating devices into a Testo 350M gas analyzer for subsequent analysis. The accuracy of the analyzer for each species measurement is 1% for O2 and 5% for CO. Each sensor was calibrated before measurement. COmax is 10,000 ppm in this experiment.The difference in pressure before and after ignition is called the burner resistance. A static pressure method was used to measure ignition resistance at the position of the straight section (See Fig. 1). One end of the utube differential manometer was connected with a static pressure hole, and the other end was open to atmospheric conditions.Table 1 lists equipment used along with their technical characteristics. Table 2 lists operating parameters. Table 3 lists the final analysis and other characteristics of 0 light diesel oil used in the experiments. Table 4 records the characteristics of the bituminous pulverized coal used in the experiments. The methods used to measure calorific value, proximate analysis and ultimate analysis were in accordance with 2132003, 2122001 and 4762001 of the Chinese standards code, respectively. The pulverized coal fineness was R90 = %, . % of all particles pass through a 90 lm aperture sieve.3. Result and discussion. The gas temperature distributionFig. 2 depicts gas temperature profiles measured along the burner center line。建議從如下方面著手: 1)從生產(chǎn)工藝上,要根據(jù)設(shè)計(jì)提供的機(jī)組最小防凍流量數(shù)據(jù)合理調(diào)整機(jī)組的負(fù)荷,盡可能保證機(jī)組出力高于防凍流量對應(yīng)負(fù)荷。所以對真空系統(tǒng)的管理,應(yīng)體現(xiàn)預(yù)防為主的指導(dǎo)思想。當(dāng)上面的氣壓高于空冷島下面的氣壓時(shí)，有的風(fēng)機(jī)就會產(chǎn)生逆向流，即上升的熱空氣又被吸入風(fēng)機(jī)的入口而流過凝汽器，形成熱風(fēng)回流，風(fēng)機(jī)入口空氣溫度迅速升高，在空冷凝汽器內(nèi)的蒸汽換熱效率急劇下降，導(dǎo)致排汽壓力增大，真空迅速惡化。 (2)汽輪機(jī)排汽用空氣作為直接冷卻介質(zhì),通過鋼制散熱器進(jìn)行表面交換,故需要龐