本文選題：生物質(zhì) + 低揮發(fā)分煤��； 參考：《山東建筑大學(xué)》2014年碩士論文

【摘要】：能源危機已成為全球面臨的重大問題之一,我國的發(fā)電廠主要以火力發(fā)電為主,需要燃燒大量的煤炭資源,在我國低揮發(fā)分煤的量較大但是其揮發(fā)分含量低不易點燃。生物質(zhì)是一種揮發(fā)分含量高的可再生能源,生物質(zhì)與低揮發(fā)分煤粉混合燃燒方式既可以對生物質(zhì)能進行規(guī)模化利用又能改善低揮發(fā)分煤粉的著火特性,對生物質(zhì)和低揮發(fā)分煤粉燃燒特性的研究具有重要意義。同時,在電廠中鍋爐點火與低負荷穩(wěn)燃需要大量的煤粉及燃料油,微油點火技術(shù)是解決這一問題的有效途徑,對微油點燃生物質(zhì)和低揮發(fā)分煤粉混合物的研究具有現(xiàn)實意義。 本文研究內(nèi)容主要分為三大塊進行,以玉米秸稈、棉花秸稈、蘋果木三種生物質(zhì)和某低揮發(fā)分煤為研究對象,包括生物質(zhì)與低揮發(fā)分煤的燃燒特性熱重試驗研究、生物質(zhì)與低揮發(fā)分煤粉的污染物排放特性試驗研究及微油點火數(shù)值模擬。 由熱重試驗可以得到燃料燃燒的TG和DTG曲線,發(fā)現(xiàn)生物質(zhì)和煤粉燃燒過程經(jīng)歷水分蒸發(fā)階段、揮發(fā)分析出燃燒階段和焦炭燃燒階段三個階段,生物質(zhì)燃燒主要是揮發(fā)分析出燃燒階段,煤粉主要的失重在焦炭的燃燒階段。隨著升溫速率增大,燃燒曲線有向高溫側(cè)移動的現(xiàn)象。生物質(zhì)摻混比例越大,著火溫度降低著火會越提前,燃盡性能也越好,摻混生物質(zhì)有利于改善低揮發(fā)分煤粉的燃燒特性,使其燃燒更穩(wěn)定。 在污染物排放特性的研究中發(fā)現(xiàn)低揮發(fā)分煤粉NO的排放量上遠大于生物質(zhì)的,三種生物質(zhì)的加入都降低了NO和SO2的排放量,隨著生物質(zhì)摻混比例的增大,煤粉混合物的污染物排放量逐漸減小,生物質(zhì)對NO和SO2排放量的減小效果非常明顯,生物質(zhì)的摻混燃燒可以降低對環(huán)境造成的污染。 通過數(shù)值模擬方式對煤粉在燃燒器內(nèi)的點火過程進行了模擬,對燃燒器內(nèi)部的點火過程有了更深刻的認識；改變生物質(zhì)的摻混比例煤粉混合物的著火總體特征沒有明顯的變化,但是生物質(zhì)摻混比例越大煤粉混合物著火越提前,考慮到摻混比例過大會影響燃料的熱值及產(chǎn)生過多焦油摻混比例不能過大；一次風速度越低,著火點越靠前對煤粉點火越有利,但一次風風速降低造成空氣量不足問題和加大燃料結(jié)焦的可能性,一次風風速增大時混合燃料在燃燒器內(nèi)停留的時間會減小,燃料氣流和油火焰的熱交換的時間變短,燃料的點燃會延后,增大燃料點燃的難度,燃燒器中心線的溫度最大值越接近燃燒器的出口；顆粒尺寸越小對燃燒對點火越有利,顆粒直徑小燃料相對受熱面積大,揮發(fā)分析出會越迅速,燃料的著火燃燒性能越好,但考慮到現(xiàn)實煤粉混合物的粒徑越小對制粉系統(tǒng)的要求會越高、能耗越高,結(jié)合模擬結(jié)果本文認為煤粉混合物燃料的尺寸在0.120mm(120目)左右較理想。
[Abstract]:The energy crisis has become one of the major problems facing the whole world. The power plants in our country mainly focus on thermal power generation and need to burn a lot of coal resources. In our country, the quantity of low volatile coal is large, but the low volatile content is not easy to ignite.Biomass is a kind of renewable energy with high volatile content. The mixed combustion of biomass and low volatile pulverized coal can not only make use of biomass energy on a large scale but also improve the ignition characteristics of low volatile pulverized coal.It is of great significance to study the combustion characteristics of biomass and low volatile pulverized coal.At the same time, a large amount of pulverized coal and fuel oil are needed for boiler ignition and low load stable combustion in power plant. The micro-oil ignition technology is an effective way to solve this problem, and it is of practical significance to study the mixture of biomass and low volatile coal powder ignited by micro-oil.The research contents of this paper are divided into three parts: corn straw, cotton stalk, apple wood biomass and some low volatile coal, including the combustion characteristics of biomass and low volatile coal.Experimental study on pollutant emission characteristics of biomass and low volatile coal powder and numerical simulation of micro-oil ignition.TG and DTG curves of fuel combustion can be obtained by thermogravimetric test. It is found that the combustion process of biomass and pulverized coal goes through the water evaporation stage, and the three stages of combustion and coke combustion are analyzed by volatilization.Biomass combustion is mainly analyzed by volatilization, and the main weight loss of pulverized coal is in the combustion stage of coke.With the increase of heating rate, the combustion curve moves to the high temperature side.The higher the proportion of biomass is, the earlier the ignition temperature will be and the better the burnout performance will be. The blending of biomass can improve the combustion characteristics of low volatile coal powder and make its combustion more stable.In the study of emission characteristics of pollutants, it was found that the emission of no from low volatile pulverized coal was much larger than that from biomass. The addition of three kinds of biomass reduced the emission of no and SO2, and with the increase of biomass mixing ratio,The pollutant emission of pulverized coal mixture decreases gradually, and the effect of biomass on no and SO2 emissions is very obvious. The mixed combustion of biomass can reduce the pollution to the environment.The ignition process of pulverized coal in the burner is simulated by numerical simulation, and the ignition process inside the burner is understood more deeply, and the overall ignition characteristics of the pulverized coal mixture with different blending ratio of biomass are not changed obviously.However, the higher the ratio of biomass to coal, the earlier the ignition of pulverized coal mixture. Considering that the ratio of blending too much to the calorific value of fuel and the proportion of producing too much tar can not be too large, the lower the primary air velocity is,The closer the ignition point is, the more favorable it is to ignite the pulverized coal, but the lower the primary wind speed, the lower the air volume and the greater the possibility of coking the fuel. The residence time of the mixed fuel in the burner decreases when the primary wind speed increases.The time of heat exchange between fuel flow and oil flame becomes shorter, the ignition of fuel will be delayed, the difficulty of fuel ignition will be increased, the maximum temperature of the central line of the burner is closer to the outlet of the burner, and the smaller the particle size is, the more favorable the ignition is to the ignition.The smaller the particle diameter fuel is relative to the larger the heating area, the faster the volatilization analysis will be, and the better the ignition and combustion performance of the fuel is, but considering that the smaller the particle size of the real pulverized coal mixture is, the higher the requirement for the pulverizing system is and the higher the energy consumption is.Based on the simulation results, it is considered that the fuel size of pulverized coal mixture is about 0.120mm(120.
【學(xué)位授予單位】：山東建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM621.2

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