【作者】 陆伟群；

【导师】 房鼎业；

【作者基本信息】 华东理工大学 ， 化学工艺， 2012， 博士

【摘要】 2013年茂名石化2000万吨/年油品升级改造建成投产后,石油焦年产量达104万吨/年。根据石油焦性质,高硫石油焦主导出路是锅炉燃料,但是高硫焦市场销路不稳定,较难找到合适的固定用户。而社会一些小冶炼厂、土窑炉由于其燃烧设备简陋,没有任何脱硫设施,由此排放的二氧化硫对环境造成的污染造成较大影响。茂名石化公司2台410吨/小时CFB锅炉2005年底建成投用,根据设计,这两台CFB锅炉燃料设计为100%烟煤和70%烟煤+30%石油焦两种。按照满负荷运行,掺烧30%石油焦消耗18万吨/年,仅占茂名石化石油焦的产量的17.3%。利用CFB结构优势,通过掺烧方式提高石油焦掺烧量,为高硫焦找到一个稳定有效环保的出路,成了炼油企业急需解决的课题。本论文通过研究CFB锅炉结构特点以及锅炉运行安全性、环保要求和经济指标等影响因素,论证了燃料品质特性是影响指定CFB锅炉安全、经济、环保运行的关键因素。在理论研究的基础上,结合高硫石油焦油页岩不同混合物和脱硫剂石灰石理化分析数据,通过在西安热工研究院CFBC试验炉掺烧不同混合比例的高硫石油焦油页岩混合燃料的中试研究,初步确定CFB锅炉掺烧高硫石油焦油页岩混合燃料的可行性,首次提出在工业CFB锅炉掺烧高硫石油焦油页岩混合燃料。在半工业中试基础上,通过在茂名石化410t/h CFB锅炉实炉掺烧高硫石油焦油页岩混合燃料的工业试验,分析研究掺烧过程中存在问题,提出长期掺烧高硫石油焦油页岩混合燃料合理控制参数和设备技术改造建议,首家完成燃煤CFB锅炉掺烧高硫石油焦油页岩混合燃料工业试验。综合各方面研究结果,我们认为：对于指定CFB锅炉,通过对冷渣系统和石灰石系统能力核定、改造后或控制高硫石油焦油页岩适当的混合比例,在工业CFB锅炉燃烧高硫石油焦油页岩混合燃料在满足环保条件下是安全的、经济的。本论文主要内容如下：本论文第二章简述了CFB锅炉结构特点,阐述了CFB锅炉安全环保运行的影响因素,论述了燃料特性对CFB锅炉运行的影响。指出燃料特性对锅炉安全运行存在较大影响,明确提出锅炉燃用燃料硬度、灰熔点、硫含量、水含量、热值和灰含量必须在设计范围内,并从烟气污染物生成原理角度证明燃料特性是影响锅炉污染物达标排放唯一可控因素,燃料的热值、硫含量、灰含量是控制的关键指标。通过锅炉效率推算方法,论证对于指定锅炉,燃料品质是CFB锅炉经济运行唯一可控因素。本论文第三章是对高硫石油焦、油页岩和石灰石理化数据进行分析,研究高硫石油焦、油页岩及其混合物的低位发热量、元素组成、全硫、粒度分布、密度、灰熔点、灰成分、着火和燃尽特性、可磨性、冲刷磨损性、自脱硫能力、颗粒度分布特性以及石灰石颗粒分布特性、反应能力和活性。通过分析认为石油焦和油页岩单样个别指标超出了发电锅炉用煤划分标准,不适合单样燃用,但两种燃料按一定比例混合的混合燃料与燃煤电厂常规燃料相关指标水平接近,采用CFB锅炉技术燃用高硫石油焦油页岩适当混合比例的混合燃料可取得较理想效果。论文第四章是分析研究石油焦油页岩混合燃料在1MWth CFB试验炉燃烧、脱硫、排放及灰渣特性中试数据。研究数据表明,试验炉条件下,CFB锅炉掺烧高硫石油焦油页岩混合物能满足安全、环保和经济要求,主要依据：CFB锅炉采用床下油枪点火方式,大于420℃时混合燃料能够成功着火,床温控制在840℃-900℃,试验燃料均能稳定燃烧；飞灰可燃物含量1.91%-5.70%,底渣可燃物含量0.96%-2.42%,燃烧效率95.7%-99.05%,飞灰份额65.71%-83.90%; Ca/S=2.4, T=877.5℃时,S02排放浓度175.8-491.3 mg/m3(标,6%02),脱硫效率95.1-98.3%；NOx排放浓度321.7mg/m3-625.1 mg/m3(标,6%O2); CO排放浓度32.45 mg/m3-85.96 mg/m3,并随过量空气系数、炉膛温度等因素的不同而变化。论文第五章是分析研究中国石化集团茂名分公司410t/hCFB锅炉掺烧高硫石油焦油页岩混合燃料工业试验数据。研究数据表明,指定工业CFB锅炉掺烧高硫石油焦油页岩混合物能满足安全、环保和经济要求,主要依据：工业CFB锅炉掺烧75%石油焦和25%油页岩时,锅炉连续稳定运行,床温保持在830℃左右；飞灰平均含碳量11.5%,底渣平均含碳量4.3%,飞灰份额约35%,锅炉热效率90.89%。运行最佳参数为运行排烟氧量控制在3.6%,床下流化风率控制在50%左右,风室压力维持在11kPa以上。石灰石能力充足条件下,锅炉SO2排放浓度小于200 mg/Nm3,脱硫效率95%。氮氧化物排放浓度101.6 mg/Nm3-132.9 mg/Nm3,达到了GB13223-2003所规定的低于650 mg/m3(标,6%02)的排放要求；钙硫摩尔比3.0、床温830℃条件下,150℃时飞灰比电阻值为3.1×1011Ω·cm,较普通燃煤飞灰比电阻小得多；实炉飞灰磨损指数Hm为13.56%、14.32%,磨损特性属中等磨损。更多还原

【Abstract】 The output of petroleum coke will reach 1.04 million t/a after completion and operation of the 20 million t/a oil product upgrading and revamping project of SINOPEC CORP. Maoming COMPANY (SINOPEC Maoming) in 2013. Based upon the property of petroleum coke, the dominant outlet of high sulfur petroleum coke is boiler fuel. However, as the market for high sulfur coke is instable, it is hard to find suitable regular customers. Some small metallurgical plants and earth kilns in the community, due to shabby combustion equipment and lack of desulfurization facilities, have been causing great environmental pollutions by the carbon dioxide.SINOPEC Maoming’s 2x410 t/h CFB boilers were completed and put into operation at the end of 2005. According to the design, fuels of the two CFB boilers were 100% soft coal or 70% soft coal plus 30% petroleum coke. If calculated based on full-load operation, the two CFB boilers consume 180 K t/a by petroleum coke as 30% of the mixed combustion fuel, which, however, only accounts for 17.3% of SINOPEC Maoming’s petroleum coke output. Therefore, it has become an urgent subject for the refinery to find a stable and effective environment-friendly way out for the high sulfur coke through mixed combustion to improve the quantity of mixed combustion of petroleum coke by taking advantage of CFB structural advantages.This paper argues that fuel properties are the critical factors impacting designated CFB boilers’safety, economics and environment-friendly operation by study of CFB boilers’ construction features and such influencing factors as the boiler operation safety, environmental requirements and economic indicators. On the basis of theoretical research, in combination with the physical and chemical analysis data about different mixture of high sulfur petroleum coke and oil shale as well as the desulfurizer lime stone and by way of pilot research on mixed combustion of mixed fuels of high sulfur petroleum coke and oil shale at different blending ratios on 1MWt/h CFBC test boiler of Xi’an Thermal Power Research Institute, the feasibility of combusting mixed fuels of high sulfur petroleum coke and oil shale on CFB boilers was preliminarily determined and it was proposed for the first time to burn mixed fuels of high sulfur petroleum coke and oil shale on industrial CFB boilers. On the basis of semi-industrial pilot-scale test and through industrial test of combustion of mixed fuels of high sulfur petroleum coke and oil shale on SINOPEC Maoming’s two 410 t/h physical CFB boilers, analysis and study were conducted for problems existing in the course of mixed combustion, reasonable control parameters and recommendations for technical modification of equipment were proposed for long-term combustion of mixed fuels of high sulfur petroleum coke and oil shale. SINOPEC Maoming was the first company completing the industrial test of combusting mixed fuels of high sulfur petroleum coke and oil shale on CFB boilers. Combining various study results, we drew the conclusion that combustion of mixed fuels of high sulfur petroleum coke and oil shale on industrial CFB is safe and cost-effective for designated CFB boilers under the condition of meeting environmental requirements through capacity verification of the slag cooling system and lime stone system, control of appropriate blending ratio of high sulfur and oil shale after modifications. The paper contains the following:The second part of this paper briefly describes CFB boilers’construction features, expounds factors impacting the safe and environment-friendly operation of CFB boilers and discusses the impact of fuel properties on CFB boilers’operation. It is pointed out in the paper that the fuel properties have greater impact on safe operation of CFB boilers. In addition, it is expressly indicated that the boilers’fuel hardness, ash melting point, sulfur content, moisture content, heat value and ash content must be within the design values. It also proves from the perspective of fume pollutant generation mechanism in the paper that the fuel properties are the only controllable factor affecting compliance discharge of boiler pollutants and the fuel’s heat value, sulfur content and ash content were the critical indicators of control. It is argued through calculations of the boiler efficiency in the paper that the fuel quality is the only controllable factor for cost-effective operation of CFB.The third part of this paper analyzes the physical and chemical data of high sulfur petroleum coke, oil shale and lime stone, studied the lower heating value, element components, total sulfur, particle size distribution, density, ash melting point, ash content, ignition and burnout properties, grind ability, erosive wear, ability of self-desulfurization and particle size distribution features of high sulfur petroleum coke, oil shale and their mixture as well as the particle size distribution features, reaction capacity and activity of lime stone. Analysis reveals that some individual indicators of single sample of the petroleum coke and oil shale have exceeded the coal classification standards for power generation boiler. They are not applicable for combustion of single sample. However, indices of the mixture of such two fuels at certain ratios are close to those of conventional fuels of the coal fired power plant. Ideal effects can be achieved by combustion of mixed fuels blended with high sulfur petroleum coke and oil shale at appropriate ratio on CFB boilers.The fourth part of this paper analyzes and studies the pilot test data related to combustion of mixture of petroleum coke and oil shale on 1 MWt/h CFB testing boiler, the desulfurization, discharge and cinder property. The research data shows that combustion of mixture of high sulfur petroleum coke and oil shale on CFB under the conditions of testing boiler could meet the requirements of safety, environmental friendliness and cost-effectiveness. The main basis includes:CFB boilers adopt the mode of oil gun ignition under bed, in which the mixed fuel could successfully burn when the temperature goes higher than 420℃, the testing fuel can be stably combusted when the bed temperature is controlled between 840℃and 900℃; the content of ash flammables is 1.91%-5.70%, the content of bottom cinder flammables 0.96%-2.42%, combustion efficiency 95.7%-99.05%, the contents of fly ash 65.71%-83.90%; in the case of Ca/S=2.4 and T=877.5℃, the discharge concentration of SO2 is 175.8-491.3mg/m3(standard,6%O2) and desulfurization efficiency 95.1-98.3%; the discharge concentration of NOx is 321.7 mg/m3-625.1mg/m3 (standard,6%O2); the discharge concentration of CO is 32.45 mg/ m3-85.96mg/m3, which also changes with variations of such factors as the excess air coefficient and hearth temperature.The fifth part of this paper analyzes and studies the industrial test data related to combustion of mixed fuels of high sulfur petroleum coke and oil shale on SINOPEC Maoming’s 410 t/h CFB boilers. The research data reveals that combustion of mixture of high sulfur petroleum coke and oil shale on designated industrial CFB boilers can meet the requirements of safety, environment and cost-effectiveness. The main basis includes:when 75% petroleum coke and 25% oil shale are combusted in industrial CFB boilers, the boilers are operated in a continuous and stable manner and the bed temperature maintains at about 830℃; the average carbon content in fly ash is 11.5%, the average carbon content in bottom cinder 4.3%, the content of fly ash about 35% and the boiler’s heat efficiency 90.89%. The optimum operation parameters are that the oxygen content of operation fume discharge is controlled at 3.6%, the fluidized air rate under bed is controlled at about 50% and the pressure of air chamber is maintained above 11 kPa. Under the conditions of adequate lime stone capacity, the boiler’s concentration of SO2 discharge is less than 200mg/Nm3 and the desulfurization efficiency 95%. The concentration of NOx discharge is 101.6mg/Nm3-132.9mg/Nm3, reaching the discharge requirements of below 650 mg/m3(standard,6%O2) as specified by GB13223-2003; Under the conditions of molar ratio of calcium to sulfur 3.0 and bed temperature of 830℃, the resistance of fly ash ratio at 150℃is 3.1×1011Ω·cm, much less than that of normal bunker coal; the fly ash abrasion index of physical boiler was 13.56% and 14.32%, indicating an average abrasion of abrasion property.更多还原