【作者】 王波；

【导师】 肖云汉； 张士杰；

【作者基本信息】 中国科学院研究生院（工程热物理研究所） ， 工程热物理， 2009， 博士

【摘要】 IGCC技术是以煤为主要燃料的高效洁净能源动力系统的重要技术选择方向。输运床气化技术可有效利用高灰分高灰熔点煤种，是一种适合于我国发展煤基IGCC的气化技术。本文对基于输运床煤气化技术的IGCC系统集成进行了研究，为形成优化的IGCC系统方案提供了参考。本文分为五部分内容，具体如下：1．IGCC系统关键部件数学模型作为系统分析的基础，建立了输运床气化、低热值燃料气燃气轮机及其NOx排放、高低压空分等IGCC关键部件数学模型并进行了验证。2．IGCC中燃气轮机与空分集成研究将燃气轮机分为理想燃气轮机和实际燃气轮机两类，考虑了燃气轮机改烧低热值煤气以后的变工况性能以及NOx排放的约束，对燃气轮机与空分集成的各种方式进行了研究。得到了低压空分时不宜采用空分整体化和氮气回注，而高压空分应与氮气回注和空分整体化配合的结果。与低压空分相比，采用高压整体空分且氮气回注的系统具有较低的NOx排放和较高的系统效率。3．单元过程及参数对IGCC系统性能影响比较了设置煤气余热锅炉和激冷流程的IGCC系统性能，分析了煤气余热锅炉蒸汽参数以及煤气出口温度对IGCC系统效率的影响。结果表明设置煤气余热锅炉的流程比激冷流程系统效率高2．82个百分点，产高压蒸汽比产中压蒸汽方案系统效率高1．25个百分点。对采用注蒸汽降NOx的IGCC系统，煤气余热锅炉设置省煤器的必要性不大。针对不同热回收利用方式，设计了5种煤气低品位热利用方案并进行了比较。结果表明，通过燃料湿化和凝结水预热可有效利用煤气低品位热，与不回收这部分热量相比，可提高系统效率1．21个百分点。分析了燃料湿化方式在IGCC系统中的作用，并就燃料湿化与注蒸汽降NOx对IGCC系统效率的影响进行了比较。结果表明一定程度的燃料湿化既可以提高系统效率，同时又能降低NOx排放；从系统效率的角度看，燃料湿化降NOx优于注蒸汽；比较了输运床纯氧气化和空气气化的IGCC系统性能，结果显示采用空气气化的IGCC系统在效率、净发电功率以及NOx排放方面都有优势。对输运床气化的除尘工艺选择进行了分析，结果表明采用干法除尘的IGCC系统比湿法除尘效率高1．81个百分点。4．燃气轮机改烧低热值煤气的性能提出了一种估算燃气轮机透平冷却空气量的方法。选取了几种典型的输运床气化产煤气，对PG9351FA燃气轮机改烧中低热值煤气以后的性能进行了分析。并对燃气轮机的各种调整通流能力的措施进行了分析比较，包括提高压气机压比、减小压气机流量、增加透平通流面积、降低透平进口温度以及空分整体化等。结果表明在采用输运床纯氧气化且燃料气不稀释时，燃机无需增加通流能力；而采用输运床空气气化时，采取从燃机抽气供气化炉的方式可解决燃机通流问题。5．基于现有联合循环改造的IGCC系统设计了3种将PG9351FA天然气联合循环改造为基于输运床气化炉的IGCC的方案，对联合循环变工况性能和IGCC整体性能进行了计算。结果显示改造后燃气轮机排气流量和温度与设计工况差距不大，底循环偏离设计工况点不远；改造后的IGCC系统供电效率能达到40%以上。更多还原

【Abstract】 IGCC technology is recognized as one of the most promising clean coal technologies while transport gasifier can gasify the coal of high ash and high ash fusion point efficiently. This paper will investigate the integration aspects of transprot gasifier based IGCC system which intends to get some useful suggestions for the optimization of the IGCC power plant. The contents include five parts as follows:1. Key components models of IGCC systemAs the basis of system analysis, the components models of IGCC are built including transport gasifier, low calorific gas turbine and its NO_x emission, high and low pressure air separation units etc. The models are verified and show reasonable results thus can be used for the analysis of IGCC system.2. Integration of gas turbine and air separation unitVarious integration options between the gas turbine and air separation unit are analyzed including gas turbine air extraction, ASU nitrogen reinjection and the combination of the two options. The gas turbine characteristics, NOx constrain and the pressure of the ASU are considered in the system analysis. The affects of gas turbine air extraction and ASU nitrogen reinjection to IGCC performance is analyzed and some suggestions about the integration of gas turbine and ASU are obtained.3. The effects of unit processes on the performance of IGCC systemThe quench process and the process with syngas coolers are compared and how steam parameter and outlet syngas temperature affect the system thermal efficiency are analyzed. Results show that with a syngas cooler producing high pressure steam, IGCC system can achieve much higher efficiency than the quench process. While the efficiency is almost the same whether saturated high pressure steam or superheated steam is produced. Besides that, for a system with NO_X reduction by steam injection, the equipment of an economizer at the downflow of the syngas cooler seems not necessary.Low temperature heat utilization of the syngas is discussed and five cases are compared. Results show that by fuel saturation and condensate preheating, the low temperature heat of the syngas can be used efficiently and improve the system efficiency by 1.21 percent. How the fuel saturation benefits the IGCC system is studied and compared to steam injection method when using water as the dilution to reduce NO_x emission of the gas turbine. The fuel saturation show more favorable performance than steam injection. The comparison of oxygen blown transport gasifier and air blown gasifier show that IGCC based on an air blown gasifier has higher efficiency, more power output and lower NO_x emission. Finally different particulate removal methods are compared, and the results show that system with a dry filter has higher efficiency of 1.81 percent than that with a wet scrubber particulate removal.4. Gas turbine performance when firing low calorific coal gasA method to calculate the turbine cooling flow is given and the performance of PG9351FA gas turbine when firing typical low calorific coal gases is calculated. Various methods to increase the surge margin and to decrease the power output are compared including compressor pressure ratio increase, compressor flow reduction, turbine critical area increase, turbine inlet temperature decrease and the compressor air extraction. Results show that to close the IGV can reduce the power output of gas turbine but have little effect on the increase of surge margin. When firing syngas produced by oxygen blown transport gasifier with no dilution, the gas turbine power and surge margin can meet the requirement. While firing syngas produced by an air blown transport gasifier, the compressor air extraction is suggested for the operation of gas turbine.5. Retrofit natural gas combined cycle power plant with IGCCThree IGCC processes based on transport gasifier to retrofit existing natural gas combined cycle power plant is designed and analyzed. Results show that the gas turbine combined cycle can operated independently and need not to be modified significantly, and the system can achieve the overall efficiency of over 40%.更多还原