四分仓回转式空气预热器热力计算模型研究

发布时间：2018-04-12 19:41

  本文选题：四分仓回转式空预器 + 热力计算模型　； 参考：《华北电力大学》2017年硕士论文

【摘要】：未来很长一段时间内,火力发电仍将占据我国发电行业的主要地位。最近几年来,随着环保问题越来越严重,循环流化床锅炉的工程应用规模加大,并且大容量的煤粉锅炉也得到了快速的发展,由于四分仓空预器漏风率低等特点,所以四分仓空预器得到了快速的发展和应用。同时,随着锅炉加装脱硝装置以后,空预器产生低温腐蚀和积灰堵塞的问题会更加严重,因此研究四分仓空预器传热特性以及分析加装脱硝装置后对空预器的影响,对四分仓空预器的安全运行以及低温腐蚀问题有着重要的指导意义。本文针对四分仓回转式空预器的运行方式和传热特点,采用了分段集总参数法,建立了四分仓回转式空预器热力计算模型。通过Fortran语言将数学模型转化成仿真系统的一个通用算法,运用工程模块化建模的方法,借助一体化仿真支撑系统软件平台,以某300MW循环流化床锅炉的四分仓空气预热器为实例,对其进行热力计算,得到了该空预器的烟气、空气以及蓄热元件的温度分布。并在此热力计算的基础上,本文又对烟气中硫酸和硫酸氢铵的结露点进行了计算,研究了加装脱硝装置后空预器内硫酸和硫酸氢铵结露带的分布。结果表明:BMCR工况下烟气出口温度的计算值与设计值的相对偏差为0.3%,一次风出口温度计算值与设计值的相对偏差为0.2%,而左、右二次风出口温度的计算值与设计值完全吻合;并且进一步计算了三个不同工况下的出口烟温和出口风温,计算值与设计值的最大相对偏差为0.5%,从而验证模型的正确性与可靠性。转子旋转一周,随着转子角度的增加,不同工况下的烟气出口温度是逐渐增加的;金属壁温是先升高,然后慢慢降低到原来的温度。不管炉内有无脱硫,随着机组负荷的降低,硫酸氢铵和硫酸结露带的高度是增加的;加装脱硝装置后,当进口烟温降低10℃,硫酸氢氨和硫酸结露带的高度是增加的,但是硫酸氢铵结露对空预器的影响要比硫酸结露大的多;随着炉内脱硫效率的提高,各工况下空预器中硫酸氢铵结露带的高度也是降低的。
[Abstract]:Thermal power generation will still occupy the main position of power generation industry in China for a long time in the future.In recent years, with the environmental protection problem becoming more and more serious, the engineering application scale of circulating fluidized bed boiler has been enlarged, and the large capacity pulverized coal boiler has been developed rapidly, because of the low air leakage rate of the air preheater in the fourth compartment, etc.Therefore, the four-compartment air preheater has been rapidly developed and applied.At the same time, with the installation of denitrification unit in the boiler, the problems of low temperature corrosion and ash accumulation will become more serious, so the heat transfer characteristics of the air preheater and the effect of adding the denitrification device on the air preheater are studied.It has important guiding significance for safe operation of air preheater and low temperature corrosion.In view of the operation mode and heat transfer characteristics of the four-compartment rotary air preheater, a thermodynamic calculation model of the four-compartment rotary air preheater is established by using the piecewise lumped parameter method.The mathematical model is transformed into a general algorithm of the simulation system by Fortran language. By using the method of engineering modular modeling and the software platform of integrated simulation support system, the air preheater of a 300MW circulating fluidized bed boiler is taken as an example.The temperature distribution of flue gas, air and heat storage element of the air preheater is obtained by thermal calculation.On the basis of the thermodynamic calculation, the condensation point of sulphuric acid and ammonium hydrogen sulfate in flue gas is calculated, and the distribution of condensation zone of sulfuric acid and ammonium hydrogen sulfate in air preheater after adding denitrification unit is studied.The results show that the relative deviation between the calculated value of flue gas outlet temperature and the design value is 0.3, the relative deviation between the calculated value of primary air outlet temperature and the design value is 0.2 and the calculated value of left and right secondary air outlet temperature is in good agreement with the design value.The maximum relative deviation between the calculated value and the design value is 0.5, which verifies the correctness and reliability of the model.With the increase of rotor angle the outlet temperature of flue gas increases gradually and the metal wall temperature increases first and then decreases to the original temperature.Regardless of whether there is desulfurization in the furnace or not, the height of ammonium hydrogen sulfate and sulphuric acid condensation zone increases with the reduction of unit load; when the inlet smoke temperature is reduced by 10 鈩，

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