本文選題：加壓富氧燃燒　切入點：加壓TGA　出處：《北京交通大學》2017年博士論文　論文類型：學位論文

【摘要】：煤粉富氧燃燒在CO_2分離和固定領域中具有明顯的優(yōu)勢,但由于空分系統(tǒng)和CO_2凈化壓縮系統(tǒng)能耗巨大,造成系統(tǒng)的經(jīng)濟性較差,加壓富氧燃燒技術是在富氧燃燒技術的基礎上提出來的,基于加壓富氧燃燒技術的發(fā)電系統(tǒng)具有更高的發(fā)電效率,本文對0.1～5 MPa條件下煤粉的燃燒特性和加壓富氧燃燒系統(tǒng)的能耗進行了分析。本文構(gòu)建了加壓富氧近零排放發(fā)電系統(tǒng),空分制氧、煤粉燃燒、煙氣中CO_2分離壓縮過程均在高壓下進行,利用高壓煙氣冷凝器回收鍋爐排煙中水蒸氣的氣化潛熱,提高了發(fā)電系統(tǒng)效率;同時,用多級壓縮加中冷的方法液化回收煙氣中的 CO_2。在加壓氣氛下,煤粉的燃燒特性與常壓氣氛下存在很大的差別。本文應用高壓TGA 設備,研究了不同壓力(0.1 MPa,1 MPa,2 MPa,3 MPa,4 MPa、5 MPa等6種壓力條件)、不同氧氣和二氧化碳比例(21%02/79%CO_2、30%02/70%CO_2、40%02/60%CO_2等3種體積比)、不同煤種(煙煤、褐煤)條件下煤粉的燃燒和燃盡特性,獲得了燃燒動力學參數(shù)。結(jié)果顯示:相對于常壓富氧氣氛,加壓富氧氣氛下煤粉的著火溫度更低,綜合燃燒性能更好;在相同O2/CO_2比例條件下,隨著壓力的逐漸增大,煤粉的著火溫度先逐漸降低再逐漸增大,3 MPa時著火點最低,綜合燃燒性能最好;在同一壓力條件下,隨著氧氣濃度的提高,煤粉的失重提前,氧氣濃度越高,反應越劇烈;煙煤和褐煤TG曲線和DTG曲線隨壓力變化的規(guī)律是一致的,但由于兩個煤種揮發(fā)分含量的差異,在相同壓力條件下,褐煤燃燒反應速度更快;指數(shù)為1的隨機成核和隨后生長函數(shù)可以較好地表征加壓富氧條件下煤粉燃燒的動力學過程。煤粉燃燒的煙氣成分在不同的壓力條件下存在一定的區(qū)別,本文利用搭建的加壓富氧固定床試驗臺分析了不同壓力條件下煤粉燃燒煙氣成分的變化情況。結(jié)果表明:在加壓富氧條件下,煤粉的著火時間均小于常壓氣氛,燃盡時間普遍高于常壓氣氛;對于褐煤和煙煤而言,煤粉燃燒的平均溫度均高于常壓氣氛,這說明提升壓力,可以提高煤粉的燃燒強度;不論煙煤還是褐煤,各個壓力條件下氧氣濃度隨時間變化的規(guī)律是一致的,煙煤由于揮發(fā)分含量較低,初始階段不同壓力條件下O2濃度變化不明顯;適當提高反應壓力(2 MPa),煙氣中的CH4含量會提高,當壓力進一步提高,CH4的生成量會降低;煙氣中CO和CO_2的生成規(guī)律正好相反,在低壓條件下,由于煙氣流速較快,不利于煤粉顆粒和氧氣混合燃燒,造成低壓條件下煙氣中CO的濃度較高,高壓條件下,由于煙氣流速較慢,有利于煤粉完全燃燒,CO_2濃度較高,實驗條件下CO_2的最高體積濃度接近90%。以某300 MW燃煤鍋爐為研究對象,利用ASPEN PLUS軟件建立了加壓條件下煤粉富氧燃燒發(fā)電系統(tǒng)模型,研究了不同壓力條件下系統(tǒng)的能耗。隨著壓力的上升,空分制氧能耗逐漸增大,當壓力從0.1 MPa到5 MPa,制氧能耗從64.862 MW上升到115.025 MW,單位制氧能耗也從0.309kWh/m3上升到0.548 kWh/m3;煙氣壓縮系統(tǒng)的能耗隨著壓力的升高而逐漸降低,0.1 MPa時,煙氣壓縮系統(tǒng)能耗最大,為41.325 MW;隨著壓力的升高,可以從煙氣中回收水蒸氣的氣化潛熱,部分補償了空分系統(tǒng)能耗;加壓富氧燃燒系統(tǒng)相對于常壓富氧燃燒系統(tǒng),電廠凈效率更高。當壓力從0.1 MPa提升到2 MPa時,發(fā)電系統(tǒng)的凈效率從27.73%提高到29.28%,2 MPa條件下電廠凈效率最高。
[Abstract]:CO_2 has obvious advantages in separation and fixed in the field of pulverized coal oxygen enriched combustion, but because of the air separation system and purification CO_2 compression system of huge energy consumption, caused by poor economic system, pressurized oxygen enriched combustion technology is put forward based on oxygen enriched combustion technology, power generation system based on pressurized oxygen enriched combustion technology with higher generation efficiency in this paper, the energy consumption of 0.1 ~ 5 MPa in the condition of combustion characteristics of pulverized coal and pressurized oxygen enriched combustion system is analyzed. This paper constructs the pressurized oxygen enriched near zero emission power generation system, air separation, coal combustion, flue gas CO_2 separation and compression process is carried out under high pressure, the use of high pressure gas latent heat recovery boiler flue gas condenser water vapor, improve the power generation efficiency of the system; at the same time, with the method of multi-stage compression and cold recycling CO_2. in flue gas in pressurized atmosphere, the combustion of pulverized coal. There is a big difference with the normal atmosphere. The application of high voltage TGA devices of different pressure (0.1 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa and 6 pressure conditions), different proportion of oxygen and carbon dioxide (21%02/79%CO_2,30%02/70%CO_2,40%02/60%CO_2 3 volume ratio, different kinds of coal (bituminous coal)), lignite combustion and burnout characteristic of coal under the condition of the combustion kinetic parameters. The results showed that: compared with atmospheric oxygen atmosphere, pressurized oxygen enriched atmosphere pulverized coal ignition temperature lower, combustion performance is better; in the same proportion under the condition of O2 /CO_2, with the increasing of pressure, the ignition temperature of pulverized coal decreased gradually increase of 3 MPa. The lowest comprehensive combustion performance is best; in conditions under the same pressure, with the increase of oxygen concentration, mass loss of coal in advance, the oxygen concentration is higher, the violent reaction of bituminous coal and lignite; TG curve Is the consistent line and DTG curve changes with the pressure, but because of the difference of two kinds of volatile content, under the same pressure, lignite combustion reaction faster; index of 1 random nucleation and subsequent growth function can characterize the pressurized coal powder under the condition of oxygen enrichment combustion kinetics. Some differences between the composition of flue gas of pulverized coal combustion under different pressure conditions, this paper using the pressurized reactor fixed bed test rig is analyzed under different pressure conditions of pulverized coal combustion flue gas composition changes. The results show that the pressure in the oxygen rich conditions, ignition time of pulverized coal is less than atmospheric pressure atmosphere, combustion time is generally higher than the atmosphere pressure; for lignite and bituminous coal, the average temperature of pulverized coal combustion is higher than that of normal atmosphere, indicating that the lifting pressure can increase the intensity of combustion of pulverized coal; bituminous coal is also no lignite, respectively Is a concentration of oxygen under pressure varies with time, because the coal volatile content is low, the initial stage under different pressure conditions O2 concentration did not change significantly; increase the reaction pressure (2 MPa), CH4 content in the flue gas will increase further when the pressure increases, the amount of CH4 will decrease; the formation of CO and CO_2 in flue gas on the contrary, under the condition of low pressure, the gas flow rate is fast, is not conducive to the pulverized coal and oxygen mixed combustion, resulting in higher concentration of flue gas under low pressure in CO, under the condition of high pressure, the flue gas flow rate is slow, is conducive to the pulverized coal complete combustion, the concentration of CO_2, the highest volume concentration under the experimental conditions of CO_2 close to 90%. with a 300 MW coal-fired boiler as the research object, a pressurized power system model under the condition of oxygen enriched combustion using ASPEN PLUS software, studied under different pressure system The consumption of energy. As the pressure rises gradually increases energy consumption of air separation, when the pressure from 0.1 MPa to 5 MPa, oxygen consumption increased from 64.862 MW to 115.025 MW, the energy consumption per unit of oxygen also increased from 0.309kWh/m3 to 0.548 kWh/m3; energy consumption of flue gas compression system decreases with the increase of pressure 0.1 MPa, compressed gas the energy consumption of the system is 41.325 MW; the largest, with the increase of pressure, water vapor latent heat of vaporization can be recovered from the flue gas, partly compensates for the air separation system of energy consumption; pressurized oxygen enriched combustion system relative to atmospheric oxygen enriched combustion system, power plant net efficiency higher. When the pressure increased from 0.1 MPa to 2 MPa, the net efficiency of power system from 27.73% to 29.28%, under the condition of 2 MPa power plant net efficiency is highest.

【學位授予單位】：北京交通大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X773;TM621.2

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